Remove use of a regex character class in resultmap (for freebsd version

Remove use of a regex character class in resultmap (for freebsd version
check).  This isn't supported by pg_regress since the recent rewrite
into C.  While we could add char classes to pg_regress.c's code, it's
not really needed at the moment: thanks to Andrew's patch to make
pg_regress always accept the 'standard' comparison file, we can just
drop the version check.