ctdb-logging: Update to use Samba style debug.h/debug.c

ctdb-logging: Update to use Samba style debug.h/debug.c

Samba's debug subsystem has changed a lot, so CTDB's logging needs
to be rewritten to be compatible.

The new debug.h/debug.c can't just be pulled in because it has some
extra dependencies into Samba's lib/util.  For now, to support the
smallest possible patch, implement a minimal subset of Samba's
debug.[ch] that just supports the DEBUG_CALLBACK logtype.

Define a callback for each logging method.

Check later to see if debug_extra (or similar) can somehow be
implemented using debug classes.

The timestamp on CTDB CLI tool and test program DEBUG() output goes
away, so update the unit test code to cope.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Volker Lendecke <vl@samba.org>