Gen_fmgrtab.sh fails with LANG=et_EE

I recently changed locale in my machine and PostgreSQL build broke.
The reason is that Gen_fmgrtab.sh uses [^A-Z] expression to sed
and the GNU people in their infinite wisdom made that locale-dependant.

As the script uses the complicated pipeline only for fmgroids.h -> FMGROIDS_H
conversion, it seems simpler to just make it explicitly set, instead to
try to work around GNU sed.

I grepped around source and did not find other instances of this.
The A-Z experssion was only in perl scripts or in configure and
configure should be fine as it explicitly resets locale.

--
marko