qemuProcessReconnect: Avoid relabeling images after migration

qemuProcessReconnect: Avoid relabeling images after migration

Restarting libvirtd on the source host at the end of migration when a
domain is already running on the destination would cause image labels to
be reset effectively killing the domain. Commit e8d0166e1d fixed similar
issue on the destination host, but kept the source always resetting the
labels, which was mostly correct except for the specific case handled by
this patch.

https://bugzilla.redhat.com/show_bug.cgi?id=1343858

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>