USE_LOCALE and unsigned char *

It currently looks like all developers are on a platform where USE_LOCALE is defined.

If it is not defined (e.g. on AIX)  I get all sorts of
Function argument assignment between types "unsigned char*" and "char*" is not allowed.

I gather unsigned char's are only supposed to show up in a USE_LOCALE environment.

backend/util/adt/varlena.c
backend/commands/copy.c
include/utils/builtins.h

Andreas