ctdb-tcp: Rename fd -> out_fd

ctdb-tcp: Rename fd -> out_fd

in_fd is coming soon.

Fix coding style violations in the affected and adjacent lines.
Modernise some debug macros and make them more consistent (e.g. drop
logging of errno when strerror(errno) is already logged.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14084

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
(cherry picked from commit c06620169fc178ea6db2631f03edf008285d8cf2)