* lib/vasnprintf.c: Enable more code for WIDE_CHAR_VERSION, because
snwprintf()/_snwprintf() (Windows) and swprintf() (Unix) don't return
the needed buffer size, like snprintf does.
* lib/wprintf-parse.h: New file, based on lib/printf-parse.h and
gettext/gettext-runtime/intl/wprintf-parse.h.
* lib/wprintf-parse.c: New file, based on
gettext/gettext-runtime/intl/printf.c.
* lib/vasnwprintf.h: New file, based on lib/vasnprintf.h and
gettext/gettext-runtime/intl/vasnwprintf.h.
* lib/vasnwprintf.c: New file.
* lib/asnwprintf.c: New file, based on lib/asnprintf.c.
* m4/vasnprintf.m4 (gl_FUNC_VASNWPRINTF): New macro.
(gl_PREREQ_VASNXPRINTF): New macro, extracted from gl_PREREQ_VASNPRINTF.
(gl_PREREQ_VASNPRINTF): Invoke it. Don't test for wcsnlen and mbrtowc.
(gl_PREREQ_VASNWPRINTF): New macro.
* modules/vasnwprintf: New file, based on modules/vasnprintf.
Collin Funk