Initial support for Haiku.

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

@@ -0,0 +1,27 @@
+// Copyright 2017 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "Common/GL/GLInterfaceBase.h"
+
+class BWindow;
+class BGLView;
+
+class cInterfaceBGL final : public cInterfaceBase
+{
+public:
+  void Swap() override;
+  void* GetFuncAddress(const std::string& name) override;
+  bool Create(void* window_handle, bool core) override;
+  bool MakeCurrent() override;
+  bool ClearCurrent() override;
+  void Shutdown() override;
+  void Update() override;
+  void SwapInterval(int interval) override;
+
+private:
+  BWindow* m_window;
+  BGLView* m_gl;
+};