Add the GPU rigid body pipeline from https://github.com/erwincoumans/experiments as a Bullet 3.x preview for Bullet 2.80

Extras/RigidBodyGpuPipeline/opencl/gpu_rigidbody_pipeline2/Win32OpenGLRenderManager.h

@@ -0,0 +1,70 @@
+/*
+Copyright (c) 2012 Advanced Micro Devices, Inc.  
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+//Originally written by Erwin Coumans
+
+
+#ifndef _WIN32_OPENGL_RENDER_MANAGER_H
+#define _WIN32_OPENGL_RENDER_MANAGER_H
+
+
+#define RM_DECLARE_HANDLE(name) typedef struct name##__ { int unused; } *name
+
+RM_DECLARE_HANDLE(RenderObjectHandle);
+
+struct InternalData2;
+
+class Win32OpenGLWindow
+{
+	protected:
+		
+		struct InternalData2*	m_data;
+		
+		void enableOpenGL();
+		
+		void disableOpenGL();
+
+		void pumpMessage();
+	
+		
+
+public:
+
+	Win32OpenGLWindow();
+
+	virtual ~Win32OpenGLWindow();
+
+	virtual	void	init(); //default implementation uses default settings for width/height/fullscreen
+
+	void	init(int width,int height, bool fullscreen=false, int colorBitsPerPixel=0, void* windowHandle=0);
+	
+	void	switchFullScreen(bool fullscreen,int width=0,int height=0,int colorBitsPerPixel=0);
+
+	virtual	void	exit();
+
+
+	virtual	void	startRendering();
+
+	virtual	void	renderAllObjects();
+
+	virtual	void	endRendering();
+
+	virtual	float	getTimeInSeconds();
+
+	virtual void	setDebugMessage(int x,int y,const char* message);
+	
+	virtual bool requestedExit();
+
+};
+
+#endif //_WIN32_OPENGL_RENDER_MANAGER_H