Fix build issue for MinGW

Fixes #2885

googletest/include/gtest/internal/gtest-port.h

@@ -2055,7 +2055,7 @@ GTEST_DISABLE_MSC_DEPRECATED_PUSH_()
 inline int ChDir(const char* dir) { return chdir(dir); }
 #endif
 inline FILE* FOpen(const char* path, const char* mode) {
-#if GTEST_OS_WINDOWS
+#if GTEST_OS_WINDOWS && !GTEST_OS_WINDOWS_MINGW
   struct wchar_codecvt : public std::codecvt<wchar_t, char, std::mbstate_t> {};
   std::wstring_convert<wchar_codecvt> converter;
   std::wstring wide_path = converter.from_bytes(path);