Move GL interface code out of the OpenGL video backend.

Source/Core/Common/GL/GLInterface/WGL.h

@@ -0,0 +1,25 @@
+// Copyright 2008 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <string>
+#include "Common/GL/GLInterfaceBase.h"
+
+class cInterfaceWGL : public cInterfaceBase
+{
+public:
+	void SwapInterval(int Interval);
+	void Swap();
+	void* GetFuncAddress(const std::string& name);
+	bool Create(void *window_handle, bool core);
+	bool MakeCurrent();
+	bool ClearCurrent();
+	void Shutdown();
+
+	void Update();
+	bool PeekMessages();
+
+	HWND m_window_handle;
+};