libbreplace: compatibility fix for AIX

libbreplace: compatibility fix for AIX

Adds macros for preprocessor compares and replaces an incomptatible
  compare with one of the new macros.
This fixes a comptability bug on AIX.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11621
Signed-off-by: Guillaume Xavier Taillon <gtaillon@ca.ibm.com>
Reviewed-by: Björn Jacke <bjacke@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Autobuild-User(master): Björn Jacke <bj@sernet.de>
Autobuild-Date(master): Tue Jun 13 09:11:56 CEST 2017 on sn-devel-144