Reverse directories order when doing 'make delete-old-dir'. This

ensures subdirectories gets removed before their parents when doing
make delete-old.

Approved by:	re (gjb)
MFC after:	2 weeks

Makefile.inc1

@@ -1673,7 +1673,7 @@ delete-old-files:
 # the Makefile parser segfault.
 	@exec 3<&0; \
 	${MAKE} -f ${.CURDIR}/Makefile.inc1 ${.MAKEFLAGS} ${.TARGET} \
-	    -V OLD_FILES -V "OLD_FILES:Musr/share/*.gz:R" | xargs -n1 | \
+	    -V OLD_FILES -V "OLD_FILES:Musr/share/*.gz:R" | xargs -n1 | sort -r | \
 	while read file; do \
 		if [ -f "${DESTDIR}/$${file}" -o -L "${DESTDIR}/$${file}" ]; then \
 			chflags noschg "${DESTDIR}/$${file}" 2>/dev/null || true; \