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

Extras/RigidBodyGpuPipeline/dynamics/basic_demo/Stubs/AdlTransform.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 Takahiro Harada
+
+
+#ifndef _ADL_TRANSFORM_H
+#define _ADL_TRANSFORM_H
+
+#include "AdlMath.h"
+#include "AdlQuaternion.h"
+#include "AdlMatrix3x3.h"
+
+struct Transform
+{
+	float4 m_translation;
+	Matrix3x3 m_rotation;
+};
+
+Transform trSetTransform(const float4& translation, const Quaternion& quat)
+{
+	Transform tr;
+	tr.m_translation = translation;
+	tr.m_rotation = qtGetRotationMatrix( quat );
+	return tr;
+}
+
+Transform trInvert( const Transform& tr )
+{
+	Transform ans;
+	ans.m_rotation = mtTranspose( tr.m_rotation );
+	ans.m_translation = mtMul1( ans.m_rotation, -tr.m_translation );
+	return ans;
+}
+
+Transform trMul(const Transform& trA, const Transform& trB)
+{
+	Transform ans; 
+	ans.m_rotation = mtMul( trA.m_rotation, trB.m_rotation );
+	ans.m_translation = mtMul1( trA.m_rotation, trB.m_translation ) + trA.m_translation;
+	return ans;
+}
+
+float4 trMul1(const Transform& tr, const float4& p)
+{
+	return mtMul1( tr.m_rotation, p ) + tr.m_translation;
+}
+
+
+#endif //_ADL_TRANSFORM_H
+