Align base::hash_map with C++11.

tools/gn/target.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef TOOLS_GN_TARGET_H_
 #define TOOLS_GN_TARGET_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 297 matching lines @@
   // Toolchain used by this target. Null until target is resolved.
   const Toolchain* toolchain_;
 
   // Output files. Null until the target is resolved.
   OutputFile link_output_file_;
   OutputFile dependency_output_file_;
 
   DISALLOW_COPY_AND_ASSIGN(Target);
 };
 
-namespace BASE_HASH_NAMESPACE {
-
-#if defined(COMPILER_GCC)
-template<> struct hash<const Target*> {
-  std::size_t operator()(const Target* t) const {
-    return reinterpret_cast<std::size_t>(t);
-  }
-};
-#elif defined(COMPILER_MSVC)
-inline size_t hash_value(const Target* t) {
-  return reinterpret_cast<size_t>(t);
-}
-#endif  // COMPILER...
-
-}  // namespace BASE_HASH_NAMESPACE
-
 #endif  // TOOLS_GN_TARGET_H_