Workaround: postconf build did not abort if the m4 command
is not installed (on a system that does have the make command,
the awk command, the perl command, and the C compiler?!).
File: postconf/extract_cfg.sh.

Portability: slight differences between MySQL and MariaDB.
Olli Hauer. File: global/dict_mysql.c.

Bugfix (introduced: 19990302): when luser_relay specifies
a non-existent local address, the luser_relay feature becomes
a black hole. Reported by Juergen Thomsen. File: local/unknown.c.

Portability: FreeBSD 11 is supported. Files: makedefs,
util/sys_defs.h.