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_pipeline/btConvexUtility.h

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+
+/*
+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 _BT_CONVEX_UTILITY_H
+#define _BT_CONVEX_UTILITY_H
+
+#include "LinearMath/btAlignedObjectArray.h"
+#include "LinearMath/btVector3.h"
+
+struct btFace
+{
+	btAlignedObjectArray<int>	m_indices;
+//	btAlignedObjectArray<int>	m_connectedFaces;
+	btScalar	m_plane[4];
+};
+
+class btConvexUtility
+{
+	public:
+		
+	btAlignedObjectArray<btVector3>	m_vertices;
+	btAlignedObjectArray<btFace>	m_faces;
+	
+	bool	initializePolyhedralFeatures(const btAlignedObjectArray<btVector3>& orgVertices, bool mergeCoplanarTriangles);
+		
+};
+#endif
+