Added cancel callbacks to modal operators which allocates memory

in invoke callback. This prevents unfreed memory blocks when quiting
Bledner with modal operator running.

source/blender/editors/space_logic/logic_buttons.c

@@ -206,6 +206,7 @@ void LOGIC_OT_links_cut(wmOperatorType *ot)
 	ot->invoke= WM_gesture_lines_invoke;
 	ot->modal= WM_gesture_lines_modal;
 	ot->exec= cut_links_exec;
+	ot->cancel= WM_gesture_lines_cancel;
 	
 	ot->poll= ED_operator_logic_active;