Fix make clobber in 1990/fubar

1989/fubar/Makefile

@@ -205,7 +205,7 @@ clean:
 clobber: clean
 	${RM} -f ${TARGET} ${ALT_TARGET}
 	${RM} -rf *.dSYM
-	${RM} -f ouroboros.c
+	${RM} -f ouroboros.c x x1
 	@-if [ -e sandwich ]; then \
 	    ${RM} -f sandwich; \
 	    echo 'ate sandwich'; \