Two-argument free functions are uncommon; match the style elsewhere
by caching the callback at creation.

* src/util/hash.h (virHashCreate, virHashFree): Move deallocator
argument to creation.
* cfg.mk (useless_free_options): Add virHashFree.
* src/util/hash.c (_virHashTable): Track deallocator.
(virHashCreate, virHashFree): Update to new signature.
* src/conf/domain_conf.c (virDomainObjListDeinit)
(virDomainObjListInit, virDomainDiskDefForeachPath)
(virDomainSnapshotObjListDeinit, virDomainSnapshotObjListInit):
Update callers.
* src/conf/nwfilter_params.c (virNWFilterHashTableFree)
(virNWFilterHashTableCreate): Likewise.
* src/conf/nwfilter_conf.c (virNWFilterTriggerVMFilterRebuild):
Likewise.
* src/cpu/cpu_generic.c (genericHashFeatures, genericBaseline):
Likewise.
* src/xen/xm_internal.c (xenXMOpen, xenXMClose): Likewise.
* src/nwfilter/nwfilter_learnipaddr.c (virNWFilterLearnInit)
(virNWFilterLearnShutdown): Likewise.
* src/qemu/qemu_command.c (qemuDomainPCIAddressSetCreate)
(qemuDomainPCIAddressSetFree): Likewise.
* src/qemu/qemu_process.c (qemuProcessWaitForMonitor): Likewise.

libvirt-tck was failing several domain tests [1] with qemu 0.14, which
is now less tolerable of specifying 2 bootroms with the same boot index [2].

Drop the 'boot=on' param if kernel has been specfied.

[1] https://www.redhat.com/archives/libvir-list/2011-February/msg00559.html
[2] http://lists.nongnu.org/archive/html/qemu-devel/2011-02/msg01892.html

Now that the virHash handling functions call virReportOOMError by
themselves when needed, users of the virHash API no longer need to
do it by themselves. Since users of the virHash API were not
consistently calling virReportOOMError after memory failures from
the virHash code, this has the added benefit of making OOM
reporting from this code more consistent and reliable.

An upcoming patch has a use for a tap device to be created that
doesn't need to be actually put into the "up" state, and keeping it
"down" keeps the output of ifconfig from being unnecessarily cluttered
(ifconfig won't show down interfaces unless you add "-a").

bridge.[ch]: add "up" as an arg to brAddTap()
uml_conf.c, qemu_command.c: add "up" (set to "true") to brAddTap() call.

This is in response to:

   https://bugzilla.redhat.com/show_bug.cgi?id=629662

Explanation

qemu's virtio-net-pci driver allows setting the algorithm used for tx
packets to either "bh" or "timer". This is done by adding ",tx=bh" or
",tx=timer" to the "-device virtio-net-pci" commandline option.

'bh' stands for 'bottom half'; when this is set, packet tx is all done
in an iothread in the bottom half of the driver. (In libvirt, this
option is called the more descriptive "iothread".)

'timer' means that tx work is done in qemu, and if there is more tx
data than can be sent at the present time, a timer is set before qemu
moves on to do other things; when the timer fires, another attempt is
made to send more data. (libvirt retains the name "timer" for this
option.)

The resulting difference, according to the qemu developer who added
the option is:

    bh makes tx more asynchronous and reduces latency, but potentially
    causes more processor bandwidth contention since the cpu doing the
    tx isn't necessarily the cpu where the guest generated the
    packets.

Solution

This patch provides a libvirt domain xml knob to change the option on
the qemu commandline, by adding a new attribute "txmode" to the
<driver> element that can be placed inside any <interface> element in
a domain definition. It's use would be something like this:

    <interface ...>
      ...
      <model type='virtio'/>
      <driver txmode='iothread'/>
      ...
    </interface>

I chose to put this setting as an attribute to <driver> rather than as
a sub-element to <tune> because it is specific to the virtio-net
driver, not something that is generally usable by all network drivers.
(note that this is the same placement as the "driver name=..."
attribute used to choose kernel vs. userland backend for the
virtio-net driver.)

Actually adding the tx=xxx option to the qemu commandline is only done
if the version of qemu being used advertises it in the output of

    qemu -device virtio-net-pci,?

If a particular txmode is requested in the XML, and the option isn't
listed in that help output, an UNSUPPORTED_CONFIG error is logged, and
the domain fails to start.

When the <driver> element (and its "name" attribute) was added to the
domain XML's interface element, a "backend" enum was simply added to
the toplevel of the virDomainNetDef struct.

Ignoring the naming inconsistency ("name" vs. "backend"), this is fine
when there's only a single item contained in the driver element of the
XML, but doesn't scale well as we add more attributes that apply to
the backend of the virtio-net driver, or add attributes applicable to
other drivers.

This patch changes virDomainNetDef in two ways:

1) Rename the item in the struct from "backend" to "name", so that
   it's the same in the XML and in the struct, hopefully avoiding
   confusion for someone unfamiliar with the function of the
   attribute.

2) Create a "driver" union within virDomainNetDef, and a "virtio"
   struct in that struct, which contains the "name" enum value.

3) Move around the virDomainNetParse and virDomainNetFormat functions
   to allow for simple plugin of new attributes without disturbing
   existing code. (you'll note that this results in a seemingly
   redundant if() in the format function, but that will no longer be
   the case as soon as a 2nd attribute is added).

In the future, new attributes for the virtio driver backend can be
added to the "virtio" struct, and any other network device backend that
needs an attribute will have its own struct added to the "driver"
union.

Move the qemudStartVMDaemon and qemudShutdownVMDaemon
methods into a separate file, renaming them to
qemuProcessStart, qemuProcessStop. All helper methods
called by these are also moved & renamed to match

* src/Makefile.am: Add qemu_process.c/.h
* src/qemu/qemu_command.c: Add qemuDomainAssignPCIAddresses
* src/qemu/qemu_command.h: Add VNC port min/max
* src/qemu/qemu_domain.c, src/qemu/qemu_domain.h: Add
  domain event queue helpers
* src/qemu/qemu_driver.c, src/qemu/qemu_driver.h: Remove
  all QEMU process startup/shutdown functions
* src/qemu/qemu_process.c, src/qemu/qemu_process.h: Add
  all QEMU process startup/shutdown functions

The code expected that host CPU architecture matches the architecture on
which libvirt runs. This is normally true but not in tests, where host
CPU is faked to produce consistent results.

* src/qemu/qemu_command.c (qemuBuildCommandLine): Don't report oom
after qemuBuildControllerDevStr, which reported its own errors.

* src/qemu/qemu_command.c (qemuParseCommandLineDisk): Report error
before cleaning def.

QEMUD_CMD_FLAG_PCI_MULTIBUS should be set in the function
qemuCapsExtractVersionInfo()

The flag QEMUD_CMD_FLAG_PCI_MULTIBUS is used in the function
qemuBuildDeviceAddressStr(). All callers get qemuCmdFlags
by the function qemuCapsExtractVersionInfo() except that
testCompareXMLToArgvFiles() in qemuxml2argvtest.c.

So we should set QEMUD_CMD_FLAG_PCI_MULTIBUS in the function
qemuCapsExtractVersionInfo() instead of qemuBuildCommandLine()
because the function qemuBuildCommandLine() does not be called
when we attach a pci device.

tests: set QEMUD_CMD_FLAG_PCI_MULTIBUS in testCompareXMLToArgvFiles()

set QEMUD_CMD_FLAG_PCI_MULTIBUS before calling qemuBuildCommandLine()
as the flags is not set by qemuCapsExtractVersionInfo().
Signed-off-by: NWen Congyang <wency@cn.fujitsu.com>

qemu 0.13.0 (at least as built for Fedora 14, and also backported to
RHEL 6.0 qemu) supported an older syntax for a spicevmc channel; it's
not as flexible (it has an implicit name and hides the chardev
aspect), but now that we support spicevmc, we might as well target
both variants.

* src/qemu/qemu_capabilities.h (QEMUD_CMD_FLAG_DEVICE_SPICEVMC):
New flag.
* src/qemu/qemu_capabilities.c (qemuCapsParseDeviceStr): Set it
correctly.
* src/qemu/qemu_command.h (qemuBuildVirtioSerialPortDevStr): Drop
declaration.
* src/qemu/qemu_command.c (qemuBuildVirtioSerialPortDevStr): Alter
signature, check flag.
(qemuBuildCommandLine): Adjust caller and check flag.
* tests/qemuhelptest.c (mymain): Update test.
* tests/qemuxml2argvtest.c (mymain): New test.
* tests/qemuxml2argvdata/qemuxml2argv-channel-spicevmc-old.xml:
New file.
* tests/qemuxml2argvdata/qemuxml2argv-channel-spicevmc-old.args:
Likewise.

Adds <smartcard mode='passthrough' type='spicevmc'/>, which uses the
new <channel name='smartcard'/> of <graphics type='spice'>.

* docs/schemas/domain.rng: Support new XML.
* docs/formatdomain.html.in: Document it.
* src/conf/domain_conf.h (virDomainGraphicsSpiceChannelName): New
enum value.
(virDomainChrSpicevmcName): New enum.
(virDomainChrSourceDef): Distinguish spicevmc types.
* src/conf/domain_conf.c (virDomainGraphicsSpiceChannelName): Add
smartcard.
(virDomainSmartcardDefParseXML): Parse it.
(virDomainChrDefParseXML, virDomainSmartcardDefParseXML): Set
spicevmc name.
(virDomainChrSpicevmc): New enum conversion functions.
* src/libvirt_private.syms: Export new functions.
* src/qemu/qemu_command.c (qemuBuildChrChardevStr): Conditionalize
name.
* tests/qemuxml2argvtest.c (domain): New test.
* tests/qemuxml2argvdata/qemuxml2argv-smartcard-passthrough-spicevmc.args:
New file.
* tests/qemuxml2argvdata/qemuxml2argv-smartcard-passthrough-spicevmc.xml:
Likewise.

Inspired by https://bugzilla.redhat.com/show_bug.cgi?id=615757

Add a new character device backend for virtio serial channels that
activates the QEMU spice agent on the main channel using the vdagent
spicevmc connection.  The <target> must be type='virtio', and supports
an optional name that specifies how the guest will see the channel
(for now, name must be com.redhat.spice.0).

<channel type='spicevmc'>
  <target type='virtio'/>
  <address type='virtio-serial' controller='1' bus='0' port='3'/>
</channel>

* docs/schemas/domain.rng: Support new XML.
* docs/formatdomain.html.in: Document it.
* src/conf/domain_conf.h (virDomainChrType): New enum value.
* src/conf/domain_conf.c (virDomainChr): Add spicevmc.
(virDomainChrDefParseXML, virDomainChrSourceDefParseXML)
(virDomainChrDefParseTargetXML): Parse and enforce proper use.
(virDomainChrSourceDefFormat, virDomainChrDefFormat): Format.
* src/qemu/qemu_command.c (qemuBuildChrChardevStr)
(qemuBuildCommandLine): Add qemu support.
* tests/qemuxml2argvtest.c (domain): New test.
* tests/qemuxml2argvdata/qemuxml2argv-channel-spicevmc.xml: New
file.
* tests/qemuxml2argvdata/qemuxml2argv-channel-spicevmc.args:
Likewise.
Signed-off-by: NEric Blake <eblake@redhat.com>

* src/qemu/qemu_command.c (qemuBuildCommandLine): Emit smartcard
options.
(qemuAssignDeviceAliases): Assign an alias for smartcards.
(qemuBuildControllerDevStr): Manage the usb-ccid controller.
* tests/qemuxml2argvtest.c (mymain): Add new tests.
* tests/qemuxml2argvdata/qemuxml2argv-smartcard-host.args: New
file.
* tests/qemuxml2argvdata/qemuxml2argv-smartcard-host-certificates.args:
Likewise.
* tests/qemuxml2argvdata/qemuxml2argv-smartcard-passthrough.args:
Likewise.
* tests/qemuxml2argvdata/qemuxml2argv-smartcard-controller.args:
Likewise.

Depending if the qemu binary supports multiple pci-busses, the device
options will contain "bus=pci" or "bus=pci.0".

Only x86_64 and i686 seem to have support for multiple PCI-busses. When
a guest of these architectures is started, set the
QEMUD_CMD_FLAG_PCI_MULTIBUS flag.
Signed-off-by: NNiels de Vos <ndevos@redhat.com>

Command line building for incoming tunneled migration is missed,
as a result, all the tunneled migration will fail with "unknown
migration protocol".

* src/qemu/qemu_command.c

Use it in all places where a memory or storage request size is converted
to a larger granularity. This avoids requesting too small memory or storage
sizes that could result from the truncation done by a simple division.

This extends the round up fix in 6002e040
to the whole codebase.

Instead of reporting errors for odd values in the VMX code round them up.

Update the QEMU Argv tests accordingly as the original memory size 219200
isn't a even multiple of 1024 and is rounded up to 215 megabyte now. Change
it to 219100 and 219136. Use two different values intentionally to make
sure that rounding up works.

Update virsh.pod accordingly, as rounding down and rejecting are replaced
by rounding up.

qemu allows the user to choose what io storage api should be used,
either the default (threads) or native (linux aio) which in the latter
case can result in better performance.

Based on a patch originally by Matthias Dahl.

Red Hat Bugzilla #591703
Signed-off-by: NEric Blake <eblake@redhat.com>

When attaching device from a xml file and the device is mis-configured,
virsh gives mis-leading message "out of memory". This patch fixes this.
Signed-off-by: NEric Blake <eblake@redhat.com>

* src/qemu/qemu_command.c (qemuBuildChrChardevStr): Alter the
chardev alias.
(qemuBuildCommandLine): Output an id for the chardev counterpart.
* tests/qemuxml2argvdata/*: Update tests to match.
Reported by Daniel P. Berrange.

In QEMU, the card itself is a PCI device, but it requires a codec
(either -device hda-output or -device hda-duplex) to actually output
sound. Specifying <sound model='ich6'/> gives us -device intel-hda
-device hda-duplex I think it's important that a simple <sound model='ich6'/>
sets up a useful codec, to have consistent behavior with all other sound cards.

This is basically Dan's proposal of

    <sound model='ich6'>
        <codec type='output' slot='0'/>
        <codec type='duplex' slot='3'/>
    </sound>

without the codec bits implemented.

The important thing is to keep a consistent API here, we don't want some
<sound> devs require tweaking codecs but not others. Steps I see to
accomplishing this:

    - every <sound> device has a <codec type='default'/> (unless codecs are
        manually specified)
    - <codec type='none'/> is required to specify 'no codecs'
    - new audio settings like mic=on|off could then be exposed in
        <sound> or <codec> in a consistent manner for all sound models

v2:
    Use model='ich6'

v3:
    Use feature detection, from eblake
    Set codec id, bus, and cad values

v4:
    intel-hda isn't supported if -device isn't available

v5:
    Comment spelling fixes

If vnc_auto_unix_socket is enabled, any VNC devices without a hardcoded
listen or socket value will be setup to serve over a unix socket in
/var/lib/libvirt/qemu/$vmname.vnc.

We store the generated socket path in the transient VM definition at
CLI build time.

QEMU supports serving VNC over a unix domain socket rather than traditional
TCP host/port. This is specified with:

<graphics type='vnc' socket='/foo/bar/baz'/>

This provides better security access control than VNC listening on
127.0.0.1, but will cause issues with tools that rely on the lax security
(virt-manager in fedora runs as regular user by default, and wouldn't be
able to access a socket owned by 'qemu' or 'root').

Also not currently supported by any clients, though I have patches for
virt-manager, and virt-viewer should be simple to update.

v2:
    schema: Make listen vs. socket a <choice>

Report VIR_ERR_CONFIG_UNSUPPORTED instead of VIR_ERR_INTERNAL_ERROR,
as it's valid in our domain schema, just unsupported by hypervisor
here.

* src/qemu/qemu_command.c

https://bugzilla.redhat.com/show_bug.cgi?id=620363

When using -incoming stdio or -incoming exec:, qemu keeps the
stdin fd open long after the migration is complete.  Not to
mention that exec:cat is horribly inefficient, by doubling the
I/O and going through a popen interface in qemu.

The new -incoming fd: of qemu 0.12.0 closes the fd after using
it, and allows us to bypass an intermediary cat process for
less I/O.

* src/qemu/qemu_command.h (qemuBuildCommandLine): Add parameter.
* src/qemu/qemu_command.c (qemuBuildCommandLine): Support
migration via fd: when possible.  Consolidate migration handling
into one spot, now that it is more complex.
* src/qemu/qemu_driver.c (qemudStartVMDaemon): Update caller.
* tests/qemuxml2argvtest.c (mymain): Likewise.
* tests/qemuxml2argvdata/qemuxml2argv-restore-v2-fd.args: New file.
* tests/qemuxml2argvdata/qemuxml2argv-restore-v2-fd.xml: Likewise.

Support for this is included in qemu and seabios from upstream git.

This is in response to a request in:

   https://bugzilla.redhat.com/show_bug.cgi?id=665293

In short, under heavy load, it's possible for qemu's networking to
lock up due to the tap device's default 1MB sndbuf being
inadequate. adding "sndbuf=0" to the qemu commandline -netdevice
option will alleviate this problem (sndbuf=0 actually sets it to
0xffffffff).

Because we must be able to explicitly specify "0" as a value, the
standard practice of "0 means not specified" won't work here. Instead,
virDomainNetDef also has a sndbuf_specified, which defaults to 0, but
is set to 1 if some value was given.

The sndbuf value is put inside a <tune> element of each <interface> in
the domain. The intent is that further tunable settings will also be
placed inside this element.

     <interface type='network'>
       ...
       <tune>
         <sndbuf>0</sndbuf>
       ...
       </tune>
     </interface>

This patch is in response to

  https://bugzilla.redhat.com/show_bug.cgi?id=643050

The existing libvirt support for the vhost-net backend to the virtio
network driver happens automatically - if the vhost-net device is
available, it is always enabled, otherwise the standard userland
virtio backend is used.

This patch makes it possible to force whether or not vhost-net is used
with a bit of XML. Adding a <driver> element to the interface XML, eg:

     <interface type="network">
       <model type="virtio"/>
       <driver name="vhost"/>

will force use of vhost-net (if it's not available, the domain will
fail to start). if driver name="qemu", vhost-net will not be used even
if it is available.

If there is no <driver name='xxx'/> in the config, libvirt will revert
to the pre-existing automatic behavior - use vhost-net if it's
available, and userland backend if vhost-net isn't available.

* src/conf/domain_conf.h (virDomainChrDeviceType): Drop monitor.
* src/conf/domain_conf.c (virDomainChrDevice)
(virDomainChrDefParseTargetXML, virDomainChrDefFormat): Drop
monitor support.
* src/qemu/qemu_command.h (qemuBuildCommandLine): Alter signature.
* src/qemu/qemu_monitor.h (qemuMonitorOpen): Likewise.
* src/qemu/qemu_domain.h (_qemuDomainObjPrivate): Change type of
monConfig.
* src/qemu/qemu_domain.c (qemuDomainObjPrivateFree)
(qemuDomainObjPrivateXMLFormat, qemuDomainObjPrivateXMLParse):
Adjust to type change.
* src/qemu/qemu_command.c (qemuBuildCommandLine): Likewise.
* src/qemu/qemu_driver.c (qemuPrepareMonitorChr)
(qemudStartVMDaemon, qemuDomainXMLToNative, qemuConnectMonitor)
(qemudShutdownVMDaemon): Likewise.
* src/qemu/qemu_hotplug.c (qemuDomainAttachNetDevice): Likewise.
* src/qemu/qemu_monitor.c (qemuMonitorOpen): Likewise.
* tests/qemuxml2argvtest.c (testCompareXMLToArgvFiles): Likewise.

This opens up the possibility of reusing the smaller ChrSourceDef
for both qemu monitor and a passthrough smartcard device.

* src/conf/domain_conf.h (_virDomainChrDef): Factor host
details...
(_virDomainChrSourceDef): ...into new struct.
(virDomainChrSourceDefFree): New prototype.
* src/conf/domain_conf.c (virDomainChrDefFree)
(virDomainChrDefParseXML, virDomainChrDefFormat): Split...
(virDomainChrSourceDefClear, virDomainChrSourceDefFree)
(virDomainChrSourceDefParseXML, virDomainChrSourceDefFormat):
...into new functions.
(virDomainChrDefParseTargetXML): Update clients to reflect type
split.
* src/vmx/vmx.c (virVMXParseSerial, virVMXParseParallel)
(virVMXFormatSerial, virVMXFormatParallel): Likewise.
* src/xen/xen_driver.c (xenUnifiedDomainOpenConsole): Likewise.
* src/xen/xend_internal.c (xenDaemonParseSxprChar)
(xenDaemonFormatSxprChr): Likewise.
* src/vbox/vbox_tmpl.c (vboxDomainDumpXML, vboxAttachSerial)
(vboxAttachParallel): Likewise.
* src/security/security_dac.c (virSecurityDACSetChardevLabel)
(virSecurityDACSetChardevCallback)
(virSecurityDACRestoreChardevLabel)
(virSecurityDACRestoreChardevCallback): Likewise.
* src/security/security_selinux.c (SELinuxSetSecurityChardevLabel)
(SELinuxSetSecurityChardevCallback)
(SELinuxRestoreSecurityChardevLabel)
(SELinuxSetSecurityChardevCallback): Likewise.
* src/security/virt-aa-helper.c (get_files): Likewise.
* src/lxc/lxc_driver.c (lxcVmStart, lxcDomainOpenConsole):
Likewise.
* src/uml/uml_conf.c (umlBuildCommandLineChr): Likewise.
* src/uml/uml_driver.c (umlIdentifyOneChrPTY, umlIdentifyChrPTY)
(umlDomainOpenConsole): Likewise.
* src/qemu/qemu_command.c (qemuBuildChrChardevStr)
(qemuBuildChrArgStr, qemuBuildCommandLine)
(qemuParseCommandLineChr): Likewise.
* src/qemu/qemu_domain.c (qemuDomainObjPrivateXMLFormat)
(qemuDomainObjPrivateXMLParse): Likewise.
* src/qemu/qemu_cgroup.c (qemuSetupChardevCgroup): Likewise.
* src/qemu/qemu_hotplug.c (qemuDomainAttachNetDevice): Likewise.
* src/qemu/qemu_driver.c (qemudFindCharDevicePTYsMonitor)
(qemudFindCharDevicePTYs, qemuPrepareChardevDevice)
(qemuPrepareMonitorChr, qemudShutdownVMDaemon)
(qemuDomainOpenConsole): Likewise.
* src/qemu/qemu_command.h (qemuBuildChrChardevStr)
(qemuBuildChrArgStr): Delete, now that they are static.
* src/libvirt_private.syms (domain_conf.h): New exports.
* cfg.mk (useless_free_options): Update list.
* tests/qemuxml2argvtest.c (testCompareXMLToArgvFiles): Update
tests.

If the emulator doesn't support SDL graphic, we should reject
the use of SDL graphic xml with error messages, but not ignore
it silently, and pretend things are fine.

"-sdl" flag was exposed explicitly by qemu since 0.10.0, more detail:
http://www.redhat.com/archives/libvir-list/2011-January/msg00442.html

And we already have capability flag "QEMUD_CMD_FLAG_0_10", which
could be used to prevent the patch affecting the older versions
of QEMU.

* src/qemu/qemu_command.c

Skip IB700 when assigning PCI slots.

Note: the I6300ESB watchdog _is_ a PCI device.

To test this: I applied this patch to libvirt-0.8.3-2.fc14 (rebasing
it slightly: qemu_command.c didn't exist in that version) and
installed this on my machine, then tested that I could successfully
add an ib700 watchdog device to a guest, start the guest, and the
ib700 was available to the guest.  I also added an i6300esb (PCI)
watchdog to another guest, and verified that libvirt assigned a PCI
device to it, that the guest could be started, and that i6300esb was
present in the guest.

Note that if you previously had a domain with a ib700 watchdog, it
would have had an <address type='pci' .../> clause added to it in the
libvirt configuration.  This patch does not attempt to remove this.
You cannot start such a domain -- qemu gives an error if you try.
With this patch you are able to remove the bogus address element
without libvirt adding it back.
Signed-off-by: NRichard W.M. Jones <rjones@redhat.com>

The warning is bogus since strtok_r doesn't use the value when it's
first called and initializes it for the following calls.

The qemu_conf.c code is doing three jobs, driver config file
loading, QEMU capabilities management and QEMU command line
management. Move the command line code into its own file

* src/qemu/qemu_command.c, src/qemu/qemu_command.h: New
  command line management code
* src/qemu/qemu_conf.c, src/qemu/qemu_conf.h: Delete command
  line code
* src/qemu/qemu_conf.h, src/qemu_conf.c: Adapt for API renames
* src/Makefile.am: add src/qemu/qemu_command.c
* src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_text.c: Add
  import of qemu_command.h

The qemu_conf.c code is doing three jobs, driver config file
loading, QEMU capabilities management and QEMU command line
management. Move the capabilities code into its own file

* src/qemu/qemu_capabilities.c, src/qemu/qemu_capabilities.h: New
  capabilities management code
* src/qemu/qemu_conf.c, src/qemu/qemu_conf.h: Delete capabilities
  code
* src/qemu/qemu_conf.h: Adapt for API renames
* src/Makefile.am: add src/qemu/qemu_capabilities.c

* src/util/command.h (virCommandAddArgBuffer)
(virCommandAddEnvBuffer): New prototypes.
* src/util/command.c (virCommandAddArgBuffer)
(virCommandAddEnvBuffer): Implement them.
* src/libvirt_private.syms (command.h): Export them.
* src/qemu/qemu_conf.c (qemudBuildCommandLine): Use them, plugging
a memory leak on rbd_hosts in the process.