Update userdata stuff to how new box2d wants it

src/libraries/box2d/b2_joint.h

@@ -139,9 +139,6 @@ public:
 	/// Get the user data pointer.
 	b2JointUserData& GetUserData();
 
-	/// Set the user data pointer.
-	void SetUserData(b2JointUserData& userData);
-
 	/// Short-cut function to determine if either body is enabled.
 	bool IsEnabled() const;
 
@@ -223,11 +220,6 @@ inline b2JointUserData& b2Joint::GetUserData()
 	return m_userData;
 }
 
-inline void b2Joint::SetUserData(b2JointUserData& userData)
-{
-	m_userData = userData;
-}
-
 inline bool b2Joint::GetCollideConnected() const
 {
 	return m_collideConnected;