daemon: Run an external script if freeze locks were not obtained during recovery

daemon: Run an external script if freeze locks were not obtained during recovery

If the freeze child is already created in ctdb_start_freeze(), then it indicates
that the child process has not yet obtained the locks.  This may be because
another process has locked the databases and has not yet released the locks.

In this case, invoke a helper script defined by environmental variable
CTDB_DEBUG_LOCKS, to log information about locks.

Signed-off-by: Amitay Isaacs <amitay@gmail.com>