This patch adds a set of functions used in creating console streams for
domains using PTYs and ensures mutually exclusive access to the PTYs.

If mutually exclusive access is not used, two clients may open the same
console, which results in corruption on both clients as both of them
race to read data from the PTY.

Two approaches are used to ensure this:
1) Internal data structure holding open PTYs.
        This is used internally and enables the user to forcibly
        terminate another console connection eg. when somebody leaves
        the console open on another host.

2) UUCP style lock files:
        This uses UUCP lock files according to the  FHS
        ( http://www.pathname.com/fhs/pub/fhs-2.3.html#VARLOCKLOCKFILES )
        to check if other programs (like minicom) are not using the pty
        device of the console.

        This feature is disabled by default and may be enabled using
        configure parameter
        --with-console-lock-files=/path/to/lock/file/directory
        or --with-console-lock-files=auto (which tries to infer the
        location from OS used (currently only linux).

        On usual linux systems, normal users may not write to the
        /var/lock directory containing the locks. This poses problems
        while in session mode. If the current user has no access to the
        lockfile directory, check for presence of the file is still
        done, but no lock file is created. This does NOT result in an
        error.

This patch allows libvirt to add interfaces to already
existing Open vSwitch bridges. The following syntax in
domain XML file can be used:

    <interface type='bridge'>
      <mac address='52:54:00:d0:3f:f2'/>
      <source bridge='ovsbr'/>
      <virtualport type='openvswitch'>
        <parameters interfaceid='921a80cd-e6de-5a2e-db9c-ab27f15a6e1d'/>
      </virtualport>
      <address type='pci' domain='0x0000' bus='0x00'
                          slot='0x03' function='0x0'/>
    </interface>

or if libvirt should auto-generate the interfaceid use
following syntax:

    <interface type='bridge'>
      <mac address='52:54:00:d0:3f:f2'/>
      <source bridge='ovsbr'/>
      <virtualport type='openvswitch'>
      </virtualport>
      <address type='pci' domain='0x0000' bus='0x00'
                          slot='0x03' function='0x0'/>
    </interface>

It is also possible to pass an optional profileid. To do that
use following syntax:

   <interface type='bridge'>
     <source bridge='ovsbr'/>
     <mac address='00:55:1a:65:a2:8d'/>
     <virtualport type='openvswitch'>
       <parameters interfaceid='921a80cd-e6de-5a2e-db9c-ab27f15a6e1d'
                   profileid='test-profile'/>
     </virtualport>
   </interface>

To create Open vSwitch bridge install Open vSwitch and
run the following command:

    ovs-vsctl add-br ovsbr

The auto-generated WWN comply with the new addressing schema of WWN:

<quote>
the first nibble is either hex 5 or 6 followed by a 3-byte vendor
identifier and 36 bits for a vendor-specified serial number.
</quote>

We choose hex 5 for the first nibble. And for the 3-bytes vendor ID,
we uses the OUI according to underlying hypervisor type, (invoking
virConnectGetType to get the virt type). e.g. If virConnectGetType
returns "QEMU", we use Qumranet's OUI (00:1A:4A), if returns
ESX|VMWARE, we use VMWARE's OUI (00:05:69). Currently it only
supports qemu|xen|libxl|xenapi|hyperv|esx|vmware drivers. The last
36 bits are auto-generated.

Rename the src/util/netlink files to src/util/virnetlink to
better fit the naming scheme. Also rename nlComm to virNetlinkCommand.
Signed-off-by: ND. Herrendoerfer <d.herrendoerfer@herrendoerfer.name>

Curently security labels can be of type 'dynamic' or 'static'.
If no security label is given, then 'dynamic' is assumed. The
current code takes advantage of this default, and avoids even
saving <seclabel> elements with type='dynamic' to disk. This
means if you temporarily change security driver, the guests
can all still start.

With the introduction of sVirt to LXC though, there needs to be
a new default of 'none' to allow unconfined LXC containers.

This patch introduces two new security label types

 - default:  the host configuration decides whether to run the
             guest with type 'none' or 'dynamic' at guest start
 - none:     the guest will run unconfined by security policy

The 'none' label type will obviously be undesirable for some
deployments, so a new qemu.conf option allows a host admin to
mandate confined guests. It is also possible to turn off default
confinement

  security_default_confined = 1|0  (default == 1)
  security_require_confined = 1|0  (default == 0)

* src/conf/domain_conf.c, src/conf/domain_conf.h: Add new
  seclabel types
* src/security/security_manager.c, src/security/security_manager.h:
  Set default sec label types
* src/security/security_selinux.c: Handle 'none' seclabel type
* src/qemu/qemu.conf, src/qemu/qemu_conf.c, src/qemu/qemu_conf.h,
  src/qemu/libvirtd_qemu.aug: New security config options
* src/qemu/qemu_driver.c: Tell security driver about default
  config

To assist people in verifying that their host is operating in an
optimal manner, provide a 'virt-host-validate' command. For each
type of hypervisor, it will check any pre-requisites, or other
good recommendations and report what's working & what is not.

eg

  # virt-host-validate
  QEMU: Checking for device /dev/kvm                                         : FAIL (Check that the 'kvm-intel' or 'kvm-amd' modules are loaded & the BIOS has enabled virtualization)
  QEMU: Checking for device /dev/vhost                                       : WARN (Load the 'vhost_net' module to improve performance of virtio networking)
  QEMU: Checking for device /dev/net/tun                                     : PASS
   LXC: Checking for Linux >= 2.6.26                                         : PASS

This warns people if they have vmx/svm, but don't have /dev/kvm. It
also warns about missing /dev/vhost net.

In preparation for the patch to include Murmurhash3, which
introduces a virhashcode.h and virhashcode.c files, rename
the existing hash.h and hash.c to virhash.h and virhash.c
respectively.

There is now a standard QEMU guest agent that can be installed
and given a virtio serial channel

    <channel type='unix'>
      <source mode='bind' path='/var/lib/libvirt/qemu/f16x86_64.agent'/>
      <target type='virtio' name='org.qemu.guest_agent.0'/>
    </channel>

The protocol that runs over the guest agent is JSON based and
very similar to the JSON monitor. We can't use exactly the same
code because there are some odd differences in the way messages
and errors are structured. The qemu_agent.c file is based on
a combination and simplification of qemu_monitor.c and
qemu_monitor_json.c

* src/qemu/qemu_agent.c, src/qemu/qemu_agent.h: Support for
  talking to the agent for shutdown
* src/qemu/qemu_domain.c, src/qemu/qemu_domain.h: Add thread
  helpers for talking to the agent
* src/qemu/qemu_process.c: Connect to agent whenever starting
  a guest
* src/qemu/qemu_monitor_json.c: Make variable static

Preparation for another patch that refactors common patterns
into the new file for fewer lines of code overall.

* src/util/util.h (virTypedParameterArrayClear): Move...
* src/util/virtypedparam.h: ...to new file.
(virTypedParameterArrayValidate, virTypedParameterAssign): New
prototypes.
* src/util/util.c (virTypedParameterArrayClear): Likewise.
* src/util/virtypedparam.c: New file.
* po/POTFILES.in: Mark file for translation.
* src/Makefile.am (UTIL_SOURCES): Build it.
* src/libvirt_private.syms (util.h): Split...
(virtypedparam.h): to new section.
(virkeycode.h): Sort.
* daemon/remote.c: Adjust callers.
* tools/virsh.c: Likewise.

The logging APIs need to be able to generate formatted timestamps
using only async signal safe functions. This rules out using
gmtime/localtime/malloc/gettimeday(!) and much more.

Introduce a new internal API which is async signal safe.

  virTimeMillisNowRaw replacement for gettimeofday. Uses clock_gettime
                      where available, otherwise falls back to the unsafe
                      gettimeofday

  virTimeFieldsNowRaw  replacements for gmtime(), convert a timestamp
  virTimeFieldsThenRaw into a broken out set of fields. No localtime()
                       replacement is provided, because converting to
                       local time is not practical with only async signal
                       safe APIs.

  virTimeStringNowRaw  replacements for strftime() which print a timestamp
  virTimeStringThenRaw into a string, using a pre-determined format, with
                       a fixed size buffer (VIR_TIME_STRING_BUFLEN)

For each of these there is also a version without the Raw postfix
which raises a full libvirt error. These versions are not async
signal safe

* src/Makefile.am, src/util/virtime.c, src/util/virtime.h: New files
* src/libvirt_private.syms: New APis
* configure.ac: Check for clock_gettime in -lrt
* tests/virtimetest.c, tests/Makefile.am: Test new APIs

Add the core functions that implement the functionality of the API.
Suspend is done by using an asynchronous mechanism so that we can return
the status to the caller before the host gets suspended. This asynchronous
operation is achieved by suspending the host in a separate thread of
execution. However, returning the status to the caller is only best-effort,
but not guaranteed.

To resume the host, an RTC alarm is set up (based on how long we want to
suspend) before suspending the host. When this alarm fires, the host
gets woken up.

Suspend-to-RAM operation on a host running Linux can take upto more than 20
seconds, depending on the load of the system. (Freezing of tasks, an operation
preceding any suspend operation, is given up after a 20 second timeout).
And Suspend-to-Disk can take even more time, considering the time required
for compaction, creating the memory image and writing it to disk etc.
So, we do not allow the user to specify a suspend duration of less than 60
seconds, to be on the safer side, since we don't want to prematurely declare
failure when we only had to wait for some more time.

These APIs are used by both client and server RPC layer to handle
processing of keepalive messages.

The original patch for commit 4789fb2e considered renaming a file,
then backed out the name change, but forgot to back out the POTFILES.in
change, resulting in 'make syntax-check' failure.

This patch adds support for a systemd init service for libvirtd
and libvirt-guests. The libvirtd.service is *not* written to use
socket activation, since we want libvirtd to start on boot so it
can do guest auto-start.

The libvirt-guests.service is pretty lame, just exec'ing the
original init script for now. Ideally we would factor out the
functionality, into some shared tool.

Instead of

  ./configure --with-init-script=redhat

You can now do

  ./configure --with-init-script=systemd

Or better still:

  ./configure --with-init-script=systemd+redhat

We can also now support install of the upstart init script

* configure.ac: Add systemd, and systemd+redhat options to
  --with-init-script option
* daemon/Makefile.am: Install systemd services
* daemon/libvirtd.sysconf: Add note about unused env variable
  with systemd
* daemon/libvirtd.service.in: libvirtd systemd service unit
* libvirt.spec.in: Add scripts to installing systemd services
  and migrating from legacy init scripts
* tools/Makefile.am: Install systemd services
* tools/libvirt-guests.init.sh: Rename to tools/libvirt-guests.init.in
* tools/libvirt-guests.service.in: systemd service unit

Move the ifaceMacvtapLinkDump and ifaceGetNthParent functions
into virnetdevvportprofile.c since they are specific to that
code. This avoids polluting the headers with the Linux specific
netlink data types

* src/util/interface.c, src/util/interface.h: Move
  ifaceMacvtapLinkDump and ifaceGetNthParent functions and delete
  remaining file
* src/util/virnetdevvportprofile.c: Add ifaceMacvtapLinkDump
  and ifaceGetNthParent functions
* src/network/bridge_driver.c, src/nwfilter/nwfilter_gentech_driver.c,
  src/nwfilter/nwfilter_learnipaddr.c, src/util/virnetdevmacvlan.c:
  Remove include of interface.h

Rename the macvtap.c file to virnetdevmacvlan.c to reflect its
functionality. Move the port profile association code out into
virnetdevvportprofile.c. Make the APIs available unconditionally
to callers

* src/util/macvtap.h: rename to src/util/virnetdevmacvlan.h,
* src/util/macvtap.c: rename to src/util/virnetdevmacvlan.c
* src/util/virnetdevvportprofile.c, src/util/virnetdevvportprofile.h:
  Pull in vport association code
* src/Makefile.am, src/conf/domain_conf.h, src/qemu/qemu_conf.c,
  src/qemu/qemu_conf.h, src/qemu/qemu_driver.c: Update include
  paths & remove conditional compilation

The src/lxc/veth.c file contains APIs for managing veth devices,
but some of the APIs duplicate stuff from src/util/virnetdev.h.
Delete thed duplicate APIs and rename the remaining ones to
follow virNetDevVethXXXX

* src/lxc/veth.c, src/lxc/veth.h: Rename APIs & delete duplicates
* src/lxc/lxc_container.c, src/lxc/lxc_controller.c,
  src/lxc/lxc_driver.c: Update for API renaming

The src/util/network.c file is a dumping ground for many different
APIs. Split it up into 5 pieces, along functional lines

 - src/util/virnetdevbandwidth.c: virNetDevBandwidth type & helper APIs
 - src/util/virnetdevvportprofile.c: virNetDevVPortProfile type & helper APIs
 - src/util/virsocketaddr.c: virSocketAddr and APIs
 - src/conf/netdev_bandwidth_conf.c: XML parsing / formatting
   for virNetDevBandwidth
 - src/conf/netdev_vport_profile_conf.c: XML parsing / formatting
   for virNetDevVPortProfile

* src/util/network.c, src/util/network.h: Split into 5 pieces
* src/conf/netdev_bandwidth_conf.c, src/conf/netdev_bandwidth_conf.h,
  src/conf/netdev_vport_profile_conf.c, src/conf/netdev_vport_profile_conf.h,
  src/util/virnetdevbandwidth.c, src/util/virnetdevbandwidth.h,
  src/util/virnetdevvportprofile.c, src/util/virnetdevvportprofile.h,
  src/util/virsocketaddr.c, src/util/virsocketaddr.h: New pieces
* daemon/libvirtd.h, daemon/remote.c, src/conf/domain_conf.c,
  src/conf/domain_conf.h, src/conf/network_conf.c,
  src/conf/network_conf.h, src/conf/nwfilter_conf.h,
  src/esx/esx_util.h, src/network/bridge_driver.c,
  src/qemu/qemu_conf.c, src/rpc/virnetsocket.c,
  src/rpc/virnetsocket.h, src/util/dnsmasq.h, src/util/interface.h,
  src/util/iptables.h, src/util/macvtap.c, src/util/macvtap.h,
  src/util/virnetdev.h, src/util/virnetdevtap.c,
  tools/virsh.c: Update include files

Following the renaming of the bridge management APIs, we can now
split the source file into 3 corresponding pieces

 * src/util/virnetdev.c: APIs for any type of network interface
 * src/util/virnetdevbridge.c: APIs for bridge interfaces
 * src/util/virnetdevtap.c: APIs for TAP interfaces

* src/util/virnetdev.c, src/util/virnetdev.h,
  src/util/virnetdevbridge.c, src/util/virnetdevbridge.h,
  src/util/virnetdevtap.c, src/util/virnetdevtap.h: Copied
  from bridge.{c,h}
* src/util/bridge.c, src/util/bridge.h: Split into 3 pieces
* src/lxc/lxc_driver.c, src/network/bridge_driver.c,
  src/openvz/openvz_driver.c, src/qemu/qemu_command.c,
  src/qemu/qemu_conf.h, src/uml/uml_conf.c, src/uml/uml_conf.h,
  src/uml/uml_driver.c: Update #include directives

Currently every caller of the brXXX APIs has to store the returned
errno value and then raise an error message. This results in
inconsistent error messages across drivers, additional burden on
the callers and makes the error reporting inaccurate since it is
hard to distinguish different scenarios from 1 errno value.

* src/util/bridge.c: Raise errors instead of returning errnos
* src/lxc/lxc_driver.c, src/network/bridge_driver.c,
  src/qemu/qemu_command.c, src/uml/uml_conf.c,
  src/uml/uml_driver.c: Remove error reporting code

Domain listing, basic information retrieval and domain life cycle
management is implemented. But currently the domain XML output
lacks the complete devices section.

The driver uses OpenWSMAN to directly communicate with a Hyper-V
server over its WS-Management interface exposed via Microsoft WinRM.

The driver is based on the work of Michael Sievers. This started in
the same master program project group at the University of Paderborn
as the ESX driver.

See Michael's blog for details: http://hyperv4libvirt.wordpress.com/

Add a generator script to generate the structs and serialization
information for OpenWSMAN.

openwsman.h collects workarounds for problems in OpenWSMAN <= 2.2.6.
There are also disabled sections that would use ws_serializer_free_mem
but can't because it's broken in OpenWSMAN <= 2.2.6. Patches to fix
this have been posted upstream.

In daemons using pidfiles to protect against concurrent
execution there is a possibility that a crash may leave a stale
pidfile on disk, which then prevents later restart of the daemon.

To avoid this problem, introduce a pair of APIs which make
use of virFileLock to ensure crash-safe & race condition-safe
pidfile acquisition & releae

* src/libvirt_private.syms, src/util/virpidfile.c,
  src/util/virpidfile.h: Add virPidFileAcquire and virPidFileRelease

O_DIRECT has stringent requirements.  Rather than make lots of changes
at each site that wants to use O_DIRECT, it is easier to offload
the work through a helper process that mirrors the I/O between a
pipe and the actual direct fd, so that the other end of the pipe
no longer has to worry about constraints.

Plus, if the kernel ever gains better posix_fadvise support, then we
only have to touch a single file to let all callers benefit from a
more efficient way to avoid file system caching.

* src/util/virfile.h (virFileDirectFdFlag, virFileDirectFdNew)
(virFileDirectFdClose, virFileDirectFdFree): New prototypes.
* src/util/virdirect.c: Implement new wrapper object.
* src/libvirt_private.syms (virfile.h): Export new symbols.
* cfg.mk (useless_free_options): Add to list.
* po/POTFILES.in: Add new translations.

This tweaks the RPC generator to cope with some naming
conventions used for the QEMU specific APIs

* daemon/remote.c: Server side dispatcher
* src/remote/remote_driver.c: Client side dispatcher
* src/remote/qemu_protocol.x: Wire protocol definition
* src/rpc/gendispatch.pl: Use '$structprefix' in method
  names, fix QEMU flags and fix dispatcher method names

* src/util/virtaudit.[ch]: Rename...
* src/util/viraudit.[ch]: ...to match virAudit* API.
* src/Makefile.am (UTIL_SOURCES): Reflect rename.
* daemon/libvirtd.c: Likewise.
* po/POTFILES.in: Likewise.
* src/libvirt_private.syms: Likewise.
* src/qemu/qemu_audit.c: Likewise.

The last patch was incomplete.  The translated strings merely
moved between generated file names, rather than disappearing.

* cfg.mk (generated_files): Update generated file names.
* po/POTFILES.in: Add remote_dispatch.h

daemon/remote_dispatch_bodies.h is no longer with us and shouldn't be
searched for translatable strings.

This guts the libvirtd daemon, removing all its networking and
RPC handling code. Instead it calls out to the new virServerPtr
APIs for all its RPC & networking work

As a fallout all libvirtd daemon error reporting now takes place
via the normal internal error reporting APIs. There is no need
to call separate error reporting APIs in RPC code, nor should
code use VIR_WARN/VIR_ERROR for reporting fatal problems anymore.

* daemon/qemu_dispatch_*.h, daemon/remote_dispatch_*.h: Remove
  old generated dispatcher code
* daemon/qemu_dispatch.h, daemon/remote_dispatch.h: New dispatch
  code
* daemon/dispatch.c, daemon/dispatch.h: Remove obsoleted code
* daemon/remote.c, daemon/remote.h: Rewrite for new dispatch
  APIs
* daemon/libvirtd.c, daemon/libvirtd.h: Remove all networking
  code
* daemon/stream.c, daemon/stream.h: Update for new APIs
* daemon/Makefile.am: Link to libvirt-net-rpc-server.la

To facilitate creation of new clients using XDR RPC services,
pull alot of the remote driver code into a set of reusable
objects.

 - virNetClient: Encapsulates a socket connection to a
   remote RPC server. Handles all the network I/O for
   reading/writing RPC messages. Delegates RPC encoding
   and decoding to the registered programs

 - virNetClientProgram: Handles processing and dispatch
   of RPC messages for a single RPC (program,version).
   A program can register to receive async events
   from a client

 - virNetClientStream: Handles generic I/O stream
   integration to RPC layer

Each new client program now merely needs to define the list of
RPC procedures & events it wants and their handlers. It does
not need to deal with any of the network I/O functionality at
all.

Allow RPC servers to advertise themselves using MDNS,
via Avahi

* src/rpc/virnetserver.c, src/rpc/virnetserver.h: Allow
  registration of MDNS services via avahi
* src/rpc/virnetserverservice.c, src/rpc/virnetserverservice.h: Add
  API to fetch the listen port number
* src/rpc/virnetsocket.c, src/rpc/virnetsocket.h: Add API to
  fetch the local port number
* src/rpc/virnetservermdns.c, src/rpc/virnetservermdns.h: Represent
  an MDNS advertisement

To facilitate creation of new daemons providing XDR RPC services,
pull a lot of the libvirtd daemon code into a set of reusable
objects.

 * virNetServer: A server contains one or more services which
   accept incoming clients. It maintains the list of active
   clients. It has a list of RPC programs which can be used
   by clients. When clients produce a complete RPC message,
   the server passes this onto the corresponding program for
   handling, and queues any response back with the client.

 * virNetServerClient: Encapsulates a single client connection.
   All I/O for the client is handled, reading & writing RPC
   messages.

 * virNetServerProgram: Handles processing and dispatch of
   RPC method calls for a single RPC (program,version).
   Multiple programs can be registered with the server.

 * virNetServerService: Encapsulates socket(s) listening for
   new connections. Each service listens on a single host/port,
   but may have multiple sockets if on a dual IPv4/6 host.

Each new daemon now merely has to define the list of RPC procedures
& their handlers. It does not need to deal with any network related
functionality at all.

This provides two modules for handling SASL

 * virNetSASLContext provides the process-wide state, currently
   just a whitelist of usernames on the server and a one time
   library init call

 * virNetTLSSession provides the per-connection state, ie the
   SASL session itself. This also include APIs for providing
   data encryption/decryption once the session is established

* src/Makefile.am: Add to libvirt-net-rpc.la
* src/rpc/virnetsaslcontext.c, src/rpc/virnetsaslcontext.h: Generic
  SASL handling code

This provides two modules for handling TLS

 * virNetTLSContext provides the process-wide state, in particular
   all the x509 credentials, DH params and x509 whitelists
 * virNetTLSSession provides the per-connection state, ie the
   TLS session itself.

The virNetTLSContext provides APIs for validating a TLS session's
x509 credentials. The virNetTLSSession includes APIs for performing
the initial TLS handshake and sending/recving encrypted data

* src/Makefile.am: Add to libvirt-net-rpc.la
* src/rpc/virnettlscontext.c, src/rpc/virnettlscontext.h: Generic
  TLS handling code

Introduces a simple wrapper around the raw POSIX sockets APIs
and name resolution APIs. Allows for easy creation of client
and server sockets with correct usage of name resolution APIs
for protocol agnostic socket setup.

It can listen for UNIX and TCP stream sockets.

It can connect to UNIX, TCP streams directly, or indirectly
to UNIX sockets via an SSH tunnel or external command

* src/Makefile.am: Add to libvirt-net-rpc.la
* src/rpc/virnetsocket.c, src/rpc/virnetsocket.h: Generic
  sockets APIs
* tests/Makefile.am: Add socket test
* tests/virnetsockettest.c: New test case
* tests/testutils.c: Avoid overriding LIBVIRT_DEBUG settings
* tests/ssh.c: Dumb helper program for SSH tunnelling tests

This provides a new struct that contains a buffer for the RPC
message header+payload, as well as a decoded copy of the message
header. There is an API for applying a XDR encoding & decoding
of the message headers and payloads. There are also APIs for
maintaining a simple FIFO queue of message instances.

Expected usage scenarios are:

To send a message

   msg = virNetMessageNew()

   ...fill in msg->header fields..
   virNetMessageEncodeHeader(msg)
   ...loook at msg->header fields to determine payload filter
   virNetMessageEncodePayload(msg, xdrfilter, data)
   ...send msg->bufferLength worth of data from buffer

To receive a message

   msg = virNetMessageNew()
   ...read VIR_NET_MESSAGE_LEN_MAX of data into buffer
   virNetMessageDecodeLength(msg)
   ...read msg->bufferLength-msg->bufferOffset of data into buffer
   virNetMessageDecodeHeader(msg)
   ...look at msg->header fields to determine payload filter
   virNetMessageDecodePayload(msg, xdrfilter, data)
   ...run payload processor

* src/Makefile.am: Add to libvirt-net-rpc.la
* src/rpc/virnetmessage.c, src/rpc/virnetmessage.h: Internal
  message handling API.
* testutils.c, testutils.h: Helper for printing binary differences
* virnetmessagetest.c: Validate all XDR encoding/decoding

In a first cleanup step, make nlComm from macvtap.c commonly available
for other code to use. Since nlComm uses Linux-specific structures as
parameters it's prototype is only visible on Linux.

Sanlock is a project that implements a disk-paxos locking
algorithm. This is suitable for cluster deployments with
shared storage.

* src/Makefile.am: Add dlopen plugin for sanlock
* src/locking/lock_driver_sanlock.c: Sanlock driver
* configure.ac: Check for sanlock
* libvirt.spec.in: Add a libvirt-lock-sanlock RPM

Define the basic framework lock manager plugins. The
basic plugin API for 3rd parties to implemented is
defined in

  src/locking/lock_driver.h

This allows dlopen()able modules for alternative locking
schemes, however, we do not install the header. This
requires lock plugins to be in-tree allowing changing of
the lock manager plugin API in future.

The libvirt code for loading & calling into plugins
is in

  src/locking/lock_manager.{c,h}

* include/libvirt/virterror.h, src/util/virterror.c: Add
  VIR_FROM_LOCKING
* src/locking/lock_driver.h: API for lock driver plugins
  to implement
* src/locking/lock_manager.c, src/locking/lock_manager.h:
  Internal API for managing locking
* src/Makefile.am: Add locking code