New module 'wctype'.

New module 'wctype'.

* modules/wctype: Change to represent the wctype() substitute.
* lib/wctype.in.h (wctype): New declaration.
* lib/wctype.c: New file.
* lib/wctype-impl.h: New file.
* m4/wctype.m4: New file.
* m4/wctype_h.m4 (gl_WCTYPE_H): Test whether wctype is declared.
(gl_WCTYPE_H_DEFAULTS): Initialize GNULIB_WCTYPE.
* modules/wctype-h (Makefile.am): Substitute GNULIB_WCTYPE.
* tests/test-wctype-h-c++.cc: Test the declaration of wctype.
* doc/posix-functions/wctype.texi: Mention the new module and the
HP-UX 11.00 problem.