ctdb-recoverd: Free cluster mutex handler on failure to take lock

ctdb-recoverd: Free cluster mutex handler on failure to take lock

If nested events occur while the file descriptor handler is still
active then chaos can ensue.  For example, if a node is banned and the
lock is explicitly cancelled (e.g. due to election loss) then
double-talloc-free()s abound.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13800

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
(cherry picked from commit 621658cbed5d91d7096fc208bac2ff93a1880e7d)