* libc/include/wchar.h: Add prototype for wcsxfrm.
* libc/string/Makefile.am (GENERAL_SOURCES): Add wcsxfrm.c.
(CHEWOUT_FILES): Add wcsxfrm.def.
* libc/string/Makefile.in: Regenerate.
* libc/string/wcsxfrm.c: New file.
* libc/string/wcstrings.tex: Add wcsxfrm.