Switch to standard integer types in tools/.

tools/gn/substitution_type.cc

 // Copyright 2014 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.
 
 #include "tools/gn/substitution_type.h"
 
+#include <stddef.h>
 #include <stdlib.h>
 
 #include "tools/gn/err.h"
 
 const char* kSubstitutionNames[SUBSTITUTION_NUM_TYPES] = {
   "<<literal>>",  // SUBSTITUTION_LITERAL
 
   "{{source}}",  // SUBSTITUTION_SOURCE
   "{{output}}",  // SUBSTITUTION_OUTPUT
 
@@ skipping 170 matching lines @@
     if (!IsValidSourceSubstitution(types[i])) {
       *err = Err(origin, "Invalid substitution type.",
           "The substitution " + std::string(kSubstitutionNames[i]) +
           " isn't valid for something\n"
           "operating on a source file such as this.");
       return false;
     }
   }
   return true;
 }