More section layout code.

gold/gold.h

@@ -23,8 +23,9 @@
 # define N_(String) (String)
 #endif
 
-// Figure out how to get a hash set and a hash map.  The fallback is
-// to just use set and map.
+// Figure out how to get a hash set and a hash map.
+
+#if HAVE_TR1_UNORDERED_SET && HAVE_TR1_UNORDERED_MAP
 
 #include <tr1/unordered_set>
 #include <tr1/unordered_map>
@@ -34,6 +35,26 @@
 #define Unordered_set std::tr1::unordered_set
 #define Unordered_map std::tr1::unordered_map
 
+#elif HAVE_EXT_HASH_MAP && HAVE_EXT_HASH_SET
+
+#include <ext/hash_map>
+#include <ext/hash_set>
+
+#define Unordered_set __gnu_cxx::hash_set
+#define Unordered_map __gnu_cxx::hash_map
+
+#else
+
+// The fallback is to just use set and map.
+
+#include <set>
+#include <map>
+
+#define Unordered_set std::set
+#define Unordered_map std::map
+
+#endif
+
 namespace gold
 {