qemu_migration.c: sleep first before checking for migration status.
qemu_migration.c: sleep first before checking for migration status.

The problem with the previous implementation is,
even when qemuMigrationUpdateJobStatus() detects a migration job
has completed, it will do a sleep for 50 ms (which is unnecessary
and only adds up to the VM pause time).

Signed-off-by: Xing Lin <79bee7ee83b86e851974f80d6a51ba2f04402231@cs.utah.edu>
Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

andreabolognani/libvirt,jardasgit/libvirt,zippy2/libvirt,rlaager/libvirt,olafhering/libvirt,eskultety/libvirt,agx/libvirt,eskultety/libvirt,libvirt/libvirt,crobinso/libvirt,datto/libvirt,taget/libvirt,zippy2/libvirt,VenkatDatta/libvirt,taget/libvirt,jardasgit/libvirt,rlaager/libvirt,fabianfreyer/libvirt,olafhering/libvirt,fabianfreyer/libvirt,libvirt/libvirt,datto/libvirt,rlaager/libvirt,zippy2/libvirt,crobinso/libvirt,eskultety/libvirt,rlaager/libvirt,jfehlig/libvirt,taget/libvirt,agx/libvirt,libvirt/libvirt,datto/libvirt,rlaager/libvirt,zippy2/libvirt,libvirt/libvirt,jardasgit/libvirt,eskultety/libvirt,nertpinx/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,taget/libvirt,VenkatDatta/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,taget/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,nertpinx/libvirt,agx/libvirt,jardasgit/libvirt,eskultety/libvirt,datto/libvirt,datto/libvirt,VenkatDatta/libvirt,agx/libvirt,nertpinx/libvirt,crobinso/libvirt,crobinso/libvirt,agx/libvirt,VenkatDatta/libvirt,nertpinx/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,andreabolognani/libvirt,olafhering/libvirt,olafhering/libvirt,jfehlig/libvirt