Function mbrtoc32

library/Console-posix.cpp:148–154

// But wchar_t is 4 bytes that is a good fallback implementation
using u32string = std::wstring;
size_t mbrtoc32(u32string::value_type* c,
        const char* s,
        std::size_t n,
        std::mbstate_t* ps)
{
    return std::mbrtowc(c, s, n, ps);
}

size_t c32rtomb(char* mb,
        u32string::value_type c,