qemu: Call qemuDomainCleanupAdd from qemuMigrationJobContinue
qemu: Call qemuDomainCleanupAdd from qemuMigrationJobContinue

Every single call to qemuMigrationJobContinue needs to register a
cleanup callback in case the migrating domain dies between phases or
when migration is paused due to a failure in postcopy mode.

Let's integrate registering the callback in qemuMigrationJobContinue to
make sure the current thread does not release a migration job without
setting a cleanup callback.

Signed-off-by: Jiri Denemark <62bdf77dc47919a4d59a91822129d14633cfca81@redhat.com>
Reviewed-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>

olafhering/libvirt,jfehlig/libvirt,crobinso/libvirt,crobinso/libvirt,crobinso/libvirt,libvirt/libvirt,jfehlig/libvirt,olafhering/libvirt,olafhering/libvirt,jfehlig/libvirt,crobinso/libvirt,libvirt/libvirt,zippy2/libvirt,zippy2/libvirt,zippy2/libvirt,olafhering/libvirt,libvirt/libvirt,libvirt/libvirt,zippy2/libvirt,jfehlig/libvirt