[VS Addin] Add visual studio 2012 support

visual_studio/NativeClientVSAddIn/TestingProjects/BlankValidSolution2012/NaClProject/main.cpp

 // Copyright (c) 2012 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.
 
 /// This project is for use with the testing framework
 /// of the Visual Studio Add-in.
 /// Note that the PPAPI and NaCl configurations do not exist. These are added
 /// during testing time so that the most up-to-date settings are used.
 
 #include <string>
@@ skipping 45 matching lines @@
     return new NaClProjectInstance(instance);
   }
 };
 
 namespace pp {
 Module* CreateModule() {
   return new NaClProjectModule();
 }
 }  // namespace pp