_citrus_utf8_ctype_wcrtomb
size_t _citrus_utf8_ctype_wcrtomb(char * __restrict, wchar_t,
r = _citrus_utf8_ctype_wcrtomb(buf, wc, ps);
r = _citrus_utf8_ctype_wcrtomb(dst + o, wc, ps);
r = _citrus_utf8_ctype_wcrtomb(buf, wc, ps);
return _citrus_utf8_ctype_wcrtomb(s, wc, ps);