libc problem, setlocale() failure

[ZC Wong]

It's a fresh install from 6.0-RELEASE cd, then the port tree was fetched
directly from portsnap and everything is up to date.

The problem is that as long as LC_CTYPE is set to anything other than C (not
even en_US), setlocale(LC_CTYPE,""); will fail.

As a result hell of a lot of programmes complain about not being able to set
locale with messages like "Warning: locale not supported by C library,
locale unchanged", etc

Apparently something is wrong with libc but I have not clue how to fix it?

Zi