ctdb-locking: Reset ttimer before doing an early return

ctdb-locking: Reset ttimer before doing an early return

When timer expires, timeout handler routine sets lock_ctx->ttimer
to a newly created timer event.  However, when a node is INACTIVE,
timeout handler returns early with lock_ctx->ttimer set to the previous
timer event.  This timer event gets freed when the callback returns and
lock_ctx->ttimer remains set to already freed timer event.

Signed-off-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>