Given a PID, the QEMU driver reads /proc/$PID/cmdline and
/proc/$PID/environ to get the configuration. This is fed
into the ARGV->XML convertor to build an XML configuration
for the process.

/proc/$PID/exe is resolved to identify the full command
binary path

After checking for name/uuid uniqueness, an attempt is
made to connect to the monitor socket. If successful
then 'info status' and 'info kvm' are issued to determine
whether the CPUs are running and if KVM is enabled.

* src/qemu/qemu_driver.c: Implement virDomainQemuAttach
* src/qemu/qemu_process.h, src/qemu/qemu_process.c: Add
  qemuProcessAttach to connect to the monitor of an
  existing QEMU process

If an application is using libvirt + KVM as a piece of its
internal infrastructure to perform a specific task, it can
be desirable to guarentee the VM dies when the virConnectPtr
disconnects from libvirtd. This ensures the app can't leak
any VMs it was using. Adding VIR_DOMAIN_START_AUTOKILL as
a flag when starting guests enables this to be done.

* include/libvirt/libvirt.h.in: All VIR_DOMAIN_START_AUTOKILL
* src/qemu/qemu_driver.c: Support automatic killing of guests
  upon connection close
* tools/virsh.c: Add --autokill flag to 'start' and 'create'
  commands

Sometimes it is useful to be able to automatically destroy a guest when
a connection is closed. For example, kill an incoming migration if
the client managing the migration dies. This introduces a map between
guest 'uuid' strings and virConnectPtr objects. When a connection is
closed, any associated guests are killed off.

* src/qemu/qemu_conf.h: Add autokill hash table to qemu driver
* src/qemu/qemu_process.c, src/qemu/qemu_process.h: Add APIs
  for performing autokill of guests associated with a connection
* src/qemu/qemu_driver.c: Initialize autodestroy map

Only in drivers which use virDomainObj, drivers that query hypervisor
for domain status need to be updated separately in case their hypervisor
supports this functionality.

The reason is also saved into domain state XML so if a domain is not
running (i.e., no state XML exists) the reason will be lost by libvirtd
restart. I think this is an acceptable limitation.

Introduce a virProcessKill function that can be safely called
even when the job mutex is held. This allows virDomainDestroy
to kill any VM even if it is asleep in a monitor job. The PID
will die and the thread asleep on the monitor will then wake
up releasing the job mutex.

* src/qemu/qemu_driver.c: Kill process before using qemuProcessStop
  to ensure job is released
* src/qemu/qemu_process.c: Add virProcessKill for killing off
  QEMU processes

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