(lc_message_charset): Ditto. (loadlocale): Set charset of the "C" locale to "UTF-8" on Cygwin. * libc/stdlib/mbtowc_r.c (__mbtowc): Default to __utf8_mbtowc on Cygwin. * libc/stdlib/wctomb_r.c (__wctomb): Default to __utf8_wctomb on Cygwin.