Windows RT related code cleanup.

Windows RT sample cleanup.
Video I/O code cleanup.

samples/winrt/ImageManipulations/pch.cpp

@@ -0,0 +1,16 @@
+//*********************************************************
+//
+// Copyright (c) Microsoft. All rights reserved.
+// THIS CODE IS PROVIDED *AS IS* WITHOUT WARRANTY OF
+// ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING ANY
+// IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR
+// PURPOSE, MERCHANTABILITY, OR NON-INFRINGEMENT.
+//
+//*********************************************************
+
+//
+// pch.cpp
+// Include the standard header and generate the precompiled header.
+//
+
+#include "pch.h"