Sometimes you want to be able to start up the receiving side of a live migration
and actually be able to run monitor commands before you do the migration.
Libvirt, in particular, wants to do this for setting up the migration.  This
patch implements a "nowait" option to the receiving side so that you start up
the receiving side similar to:

qemu-kvm -M pc -S blah blah -incoming tcp://0:4444,nowait

Then you are able to interact with the monitor before the live migration takes
place.

Signed-off-by: Chris Lalancette <clalance@redhat.com>