Switch to standard integer types in tools/.

tools/gn/ordered_set.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_ORDERED_SET_H_
 #define TOOLS_GN_ORDERED_SET_H_
 
+#include <stddef.h>
+
 #include <set>
 
 // An ordered set of items. Only appending is supported. Iteration is designed
 // to be by index.
 template<typename T>
 class OrderedSet {
  private:
   typedef std::set<T> set_type;
   typedef typename set_type::const_iterator set_iterator;
   typedef std::vector<set_iterator> vector_type;
@@ skipping 42 matching lines @@
     for (size_t i = 0; i < other.size(); i++)
       push_back(other[i]);
   }
 
  private:
   set_type set_;
   vector_type ordering_;
 };
 
 #endif  // TOOLS_GN_ORDERED_SET_H_