Added msvs_target_platform_version and msvs_target_platform_minversion for winrt compilation

test/win/winrt-target-platform-version/dllmain.cc

-// Copyright (c) 2013 Google Inc. All rights reserved.
+// Copyright (c) 2015 Google Inc. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <windows.h>
 #include <wrl.h>
 #include <wrl/wrappers/corewrappers.h>
 #include <windows.graphics.display.h>
 
 using namespace Microsoft::WRL;
 using namespace Microsoft::WRL::Wrappers;
 using namespace ABI::Windows::Foundation;
 using namespace ABI::Windows::Graphics::Display;
 
 bool TryToUseSomeWinRT() {
   ComPtr<IDisplayPropertiesStatics> dp;
   HStringReference s(RuntimeClass_Windows_Graphics_Display_DisplayProperties);
   HRESULT hr = GetActivationFactory(s.Get(), dp.GetAddressOf());
   if (SUCCEEDED(hr)) {
     float dpi = 96.0f;
     if (SUCCEEDED(dp->get_LogicalDpi(&dpi))) {
       return true;
     }
   }
   return false;
 }
 
 BOOL WINAPI DllMain(HINSTANCE hinstance, DWORD reason, LPVOID reserved) {
   return TRUE;
 }