Clean also removes dSYM directories.

src/Makefile

@@ -39,6 +39,7 @@ $(MAIN) : $(MAIN).c object.c buffer.h
 clean : .FORCE
 	rm -f $(MAIN) $(MAIN).c
 	rm -f *~ $(MAIN)-output.out
+	rm -rf *.dSYM
 
 tidy : .FORCE
 	rm -f *~ $(MAIN)-tree.out