Import C++11 headers for unordered_(map|set) when using libc++ in protobuf.

third_party/protobuf/config.h

Index: third_party/protobuf/config.h
diff --git a/third_party/protobuf/config.h b/third_party/protobuf/config.h
index dcc0041c2fe5847b509398f6e600b76c3e538555..7baca04df0e2e209da7d79bab3338d4b64d20938 100644
--- a/third_party/protobuf/config.h
+++ b/third_party/protobuf/config.h
@@ -1,29 +1,43 @@
 /* config.h.  Generated from config.h.in by configure.  */
 /* config.h.in.  Generated from configure.ac by autoheader.  */
 
-/* the name of <hash_set> */
+#include <ciso646>

[brettw, 2014/04/26 15:55:13]

This seems a bit mysterious. I assume you picked this to be the simplest
"standard" header so _LIBCPP_VERSION is defined? I think we should document
this.

+
+/* the name of <hash_map> */
+#if defined(_LIBCPP_VERSION)
+#define HASH_MAP_CLASS unordered_map
+#else
 #define HASH_MAP_CLASS hash_map
+#endif
 
-/* the location of <hash_map> */
+/* the location of <unordered_map> or <hash_map> */
 #if defined(USE_STLPORT)
 #define HASH_MAP_H <hash_map>
+#elif defined(_LIBCPP_VERSION)
+#define HASH_MAP_H <unordered_map>
 #else
 #define HASH_MAP_H <ext/hash_map>
 #endif
 
 /* the namespace of hash_map/hash_set */
-#if defined(USE_STLPORT)
+#if defined(USE_STLPORT) || defined(_LIBCPP_VERSION)
 #define HASH_NAMESPACE std
 #else
 #define HASH_NAMESPACE __gnu_cxx
 #endif
 
 /* the name of <hash_set> */
+#if defined(_LIBCPP_VERSION)
+#define HASH_SET_CLASS unordered_set
+#else
 #define HASH_SET_CLASS hash_set
+#endif
 
-/* the location of <hash_set> */
+/* the location of <unordered_set> or <hash_set> */
 #if defined(USE_STLPORT)
 #define HASH_SET_H <hash_set>
+#elif defined(_LIBCPP_VERSION)
+#define HASH_SET_H <unordered_set>
 #else
 #define HASH_SET_H <ext/hash_set>
 #endif