Function utf32to8

external/utf8/cpp11.h:54–59

    }

    inline std::string utf32to8(const std::u32string& s)
    {
        std::string result;
        utf32to8(s.begin(), s.end(), std::back_inserter(result));
        return result;
    }

    inline std::u32string utf8to32(const std::string& s)
    {