wmempcpy: New module.
Reported by Paul Eggert in
<https://lists.gnu.org/archive/html/bug-gnulib/2020-05/msg00387.html>.
* lib/wchar.in.h (wmempcpy): New declaration.
* lib/wmempcpy.c: New file.
* m4/wmempcpy.m4: New file.
* m4/wchar_h.m4 (gl_WCHAR_H): Test whether wmempcpy is declared.
(gl_WCHAR_H_DEFAULTS): Initialize GNULIB_WMEMPCPY, HAVE_WMEMPCPY.
* modules/wchar (Makefile.am): Substitute GNULIB_WMEMPCPY,
HAVE_WMEMPCPY.
* modules/wmempcpy: New file.
* tests/test-wchar-c++.cc: Check the signature of wmempcpy.
* doc/glibc-functions/wmempcpy.texi: Mention the new module.
* modules/mempcpy (Description): Fix typo.