Try modifying check in hopes of passing upstream build

src/google/protobuf/stubs/hash.h

@@ -42,8 +42,9 @@
 #define GOOGLE_PROTOBUF_HAVE_HASH_SET 1
 
 // Use C++11 unordered_{map|set} if available.
-#if ((__cplusplus >= 201103L) &&                            \
-     ((__GLIBCXX__ > 20090421) || (_LIBCPP_STD_VER >= 11)))
+#if ((_LIBCPP_STD_VER >= 11) ||
+     (((__cplusplus >= 201103L) || defined(__GXX_EXPERIMENTAL_CXX0X)) &&
+      (__GLIBCXX__ > 20090421)))
 # define GOOGLE_PROTOBUF_HAS_CXX11_HASH
 
 // For XCode >= 4.6:  the compiler is clang with libc++.