Copyright and license for the iswxdigit.3 manual page

Copyright (c) Bruno Haible <haible@clisp.cons.org>

License for iswxdigit.3:

This is free documentation; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.