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/premake4.lua

@@ -0,0 +1,34 @@
+
+-- include "AMD"
+
+if os.is("Windows") then
+	
+		project "basic_bullet2_demo"
+
+		language "C++"
+				
+		kind "ConsoleApp"
+		targetdir "../../bin"
+
+  		includedirs {
+                ".",
+                "../../bullet2",
+                "../testbed",
+                	"../../rendering/Gwen",
+                }
+		
+
+		links { "testbed",
+			"bullet2",
+			"gwen"
+		}
+		
+		initOpenGL()
+		initGlut()
+	
+		files {
+		"**.cpp",
+		"**.h"
+		}
+
+end