Added Windows 8.1/Windows Phone 8.1 minimal support for creating projects that compile modules that…

test/win/enable-winrt/dllmain.cc

+// Copyright (c) 2013 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()

[scottmg, 2014/09/23 00:01:13]

nit; please reformat this to the standard style (primarily: { on same line, 2
space indents)

+{
+    ComPtr<IDisplayPropertiesStatics> dp;

[scottmg, 2014/09/23 00:01:13]

This code isn't being run in the test, afaict. Does its existence confirm
something at link time?

+    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;
+}