Drop X_LOCALE fallback for OS'es without setlocale()

C89 or bust!   This was documented as being needed for "only Lynx,
Linux-libc5, OS/2" and has never been enabled in modular builds,
since none of those platforms have had anyone step up to add support
since the X11R7 conversion to autotools.

Mostly performed with unifdef -UX_LOCALE, followed by removal of files
left without any purpose, and manual cleanup of remaining references.

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
nls: Fix transposed locale identifier for Khmer.

Signed-off-by: Benno Schulenberg <bensberg@justemail.net>
Reviewed-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>