Function UTF8ToWchar

include/tinyexr/tinyexr.h:4423–4430

#ifdef _WIN32
static inline std::wstring UTF8ToWchar(const std::string &str) {
  int wstr_size =
      MultiByteToWideChar(CP_UTF8, 0, str.data(), (int)str.size(), NULL, 0);
  std::wstring wstr(wstr_size, 0);
  MultiByteToWideChar(CP_UTF8, 0, str.data(), (int)str.size(), &wstr[0],
                      (int)wstr.size());
  return wstr;
}
#endif