init: restart sanlock groups are missing

If sanlock was started before the *first* installation of vdsm
then it is probably missing the supplementary groups and it needs
to be restarted.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=977926
Change-Id: Idd3f8ffe10f771a09d0a779b148bb2ebaf95fecc
Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/16742
Reviewed-by: Allon Mureinik <amureini@redhat.com>
Reviewed-by: Ayal Baron <abaron@redhat.com>