* MODULES.html.sh: New module wctype.

* MODULES.html.sh: New module wctype.
* lib/wctype_.h, m4/wctype.m4, modules/wctype: New files.
* lib/fnmatch.c: Don't bother to include <wchar.h> before
<wctype.h>, since the new wctype module should fix this.
* lib/quotearg.c: Include <wctype.h> unconditionally, since
the wctype module should arrange for it.
* lib/regex_internal.h: Likewise.
* m4/quotearg.m4 (gl_QUOTEARG): Don't check for wctype.h or iswprint,
since the wctype module should handle this now.
* m4/regex.m4 (gl_PREREQ_REGEX): Don't check for wctype.h.
* modules/fnmatch (Depends-on): Add wctype.
* modules/quotearg (Depends-on): Likewise.
* modules/regex (Depends-on): Likewise.