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/GlutRenderer.h

@@ -0,0 +1,59 @@
+/*
+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 GLUT_RENDERER_H
+#define GLUT_RENDERER_H
+
+#include "btGlutInclude.h"
+#include "LinearMath/btVector3.h"
+
+struct GlutRenderer
+{
+	static GlutRenderer* gDemoApplication;
+	int m_glutScreenWidth;
+	int m_glutScreenHeight;
+
+	btVector3 m_cameraPosition;
+	btVector3 m_cameraTargetPosition;
+	btScalar m_cameraDistance;
+	btVector3 m_cameraUp;
+	float m_azimuth;
+	float m_elevation;
+
+
+	GlutRenderer(int argc, char* argv[]);
+	
+	virtual void initGraphics(int width, int height);
+	virtual void cleanup() {}
+	
+	void runMainLoop();
+
+	virtual void updateScene(){};
+	
+	virtual void renderScene();
+
+	virtual void	keyboardCallback(unsigned char key, int x, int y) {};
+	virtual void	keyboardUpCallback(unsigned char key, int x, int y) {}
+	virtual void	specialKeyboard(int key, int x, int y){}
+	virtual void	specialKeyboardUp(int key, int x, int y){}
+	virtual void	resize(int w, int h);
+	virtual void	mouseFunc(int button, int state, int x, int y);
+	virtual void	mouseMotionFunc(int x,int y);
+	virtual void displayCallback();
+	
+
+};
+
+#endif //GLUT_RENDERER_H