ctdb-logging: Refactor logging code

ctdb-logging: Refactor logging code

This extracts the code from following files:
  - server/ctdb_logging.c
  - server/ctdb_logging_file.c
  - server/ctdb_logging_syslog.c

This is in preparation for each daemon (and some processes) doing
their own loging instead of relying on CTDB.

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