Align base::hash_map with C++11, part 2.

tools/gn/label.h

Index: tools/gn/label.h
diff --git a/tools/gn/label.h b/tools/gn/label.h
index 1028b3088c85f2c38141d173a17f9e62b2301684..9c4a1c6dcfde3f5126e6894a11cc4d98b7f13a11 100644
--- a/tools/gn/label.h
+++ b/tools/gn/label.h
@@ -6,7 +6,6 @@
 #define TOOLS_GN_LABEL_H_
 
 #include "base/containers/hash_tables.h"
-#include "build/build_config.h"
 #include "tools/gn/source_dir.h"
 
 class Err;
@@ -107,7 +106,6 @@ class Label {
 
 namespace BASE_HASH_NAMESPACE {
 
-#if defined(COMPILER_GCC)
 template<> struct hash<Label> {
   std::size_t operator()(const Label& v) const {
     hash<std::string> stringhash;
@@ -117,14 +115,6 @@ template<> struct hash<Label> {
            stringhash(v.toolchain_name());
   }
 };
-#elif defined(COMPILER_MSVC)
-inline size_t hash_value(const Label& v) {
-  return ((hash_value(v.dir().value()) * 131 +
-           hash_value(v.name())) * 131 +
-          hash_value(v.toolchain_dir().value())) * 131 +
-         hash_value(v.toolchain_name());
-}
-#endif  // COMPILER...
 
 }  // namespace BASE_HASH_NAMESPACE