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.

src/test/regress/resultmap

 float4/i.86-pc-mingw32=float4-exp-three-digits
-float8/i.86-.*-freebsd[234]=float8-small-is-zero
+float8/i.86-.*-freebsd=float8-small-is-zero
 float8/i.86-.*-openbsd=float8-small-is-zero
 float8/i.86-.*-netbsd=float8-small-is-zero
 float8/m68k-.*-netbsd=float8-small-is-zero