VideoCommon: Header cleanup

Also remedies places where the video backends and core rely on things
being indirectly included.

Source/Core/VideoBackends/D3D/XFBEncoder.cpp

@@ -2,6 +2,9 @@
 // Licensed under GPLv2+
 // Refer to the license.txt file included.
 
+#include "Common/CommonTypes.h"
+#include "Common/MsgHandler.h"
+#include "Common/Logging/Log.h"
 #include "VideoBackends/D3D/D3DBase.h"
 #include "VideoBackends/D3D/D3DBlob.h"
 #include "VideoBackends/D3D/D3DShader.h"