ctdb-daemon: Use path functions for socket and PID file

ctdb-daemon: Use path functions for socket and PID file

Drop the use of ctdb_set_sockname() because it complicates the memory
allocation and this is the only place it is used.  Just assign to the
relevant pointer.

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