more PyBullet PhysX preliminary work.

build3/premake4.lua

@@ -59,7 +59,12 @@
 		trigger = "enable_static_vr_plugin",
 		description = "Statically link vr plugin (in examples/SharedMemory/plugins/vrSyncPlugin)"
 	}
-
+	
+	newoption
+	{
+		trigger = "enable_physx",
+		description = "Allow optional PhysX backend for PyBullet, use pybullet.connect(pybullet.PhysX)."
+	}
 
 	newoption
 	{
@@ -638,4 +643,7 @@ end
 	include "../src/BulletDynamics"
 	include "../src/BulletCollision"
 	include "../src/LinearMath"
+	if _OPTIONS["enable_physx"] then
+		include "../src/physx"
+	end