ctdb-recovery: Recovery lock setting can now include helper command
The underlying change is to allow the cluster mutex argstring to
optionally contain a helper command. When the argument string starts
with '!' then the first word is the helper command to run. This is
now the standard way of changing the helper from the default.
CTDB_CLUSTER_MUTEX_HELPER show now only be used to change the location
of the default helper when testing.
Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>