_XimLocalMbLookupString can return a braille keysym even if _Xlcwctomb can't
convert to the current MB charset.
_XimLocalUtf8LookupString needs to set the braille keysym and status too.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Backported-to-NX-by: Ulrich Sibiller <uli42@gmx.de>