improve make clobber for 2014/endoh1

2014/endoh1/Makefile

@@ -176,6 +176,7 @@ clean:
 
 clobber: clean
 	${RM} -f ${TARGET} ${ALT_TARGET}
+	${RM} -f main.c treacle.c
 	@-if [ -e sandwich ]; then \
 	    ${RM} -f sandwich; \
 	    echo 'ate sandwich'; \