sanlock: Forbid VIR_DOMAIN_LOCK_FAILURE_RESTART

sanlock: Forbid VIR_DOMAIN_LOCK_FAILURE_RESTART

https://bugzilla.redhat.com/show_bug.cgi?id=905282
https://bugzilla.redhat.com/show_bug.cgi?id=967494

When lock failure is detected by sanlock, our sanlock_helper kill script
will try to restart (shutdown followed by start) the affected domain
when RESTART action is configured for it. While shutting down kills QEMU
and removes all its leases (which is what sanlock wants to happen),
trying to start it again just hangs because libvirt tries reacquire the
locks in the failed lock space. Hence, this action cannot be supported
by sanlock driver.

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