add TransportFSM::transport_speed(), a putative replacement for the Session method of the same name

libs/ardour/ardour/transport_fsm.h

@@ -151,6 +151,8 @@ struct TransportFSM
 
 	std::string current_state () const;
 
+	int transport_speed () const;
+
   private:
 	MotionState _motion_state;
 	ButlerState _butler_state;

libs/ardour/transport_fsm.cc

@@ -638,6 +638,20 @@ TransportFSM::enqueue (Event* ev)
 	}
 }
 
+int
+TransportFSM::transport_speed() const
+{
+	if (_motion_state == Stopped || _direction_state == Reversing) {
+		return 0;
+	}
+
+	if (_direction_state == Backwards) {
+		return -1;
+	}
+
+	return 1;
+}
+
 void
 TransportFSM::set_speed (Event const & ev)
 {