Copter: control_loiter initialises alt target

ArduCopter/control_loiter.pde

@@ -10,6 +10,8 @@ static bool loiter_init(bool ignore_checks)
     if (GPS_ok() || ignore_checks) {
         // set target to current position
         wp_nav.init_loiter_target();
+        // initialise altitude target to stopping point
+        pos_control.set_target_to_stopping_point_z();
         return true;
     }else{
         return false;