Found another one. Why does mdconfig hate me? Add a "sleep 5" to

this script, without it sparc64 ISO building was consistently failing
because the /dev/md0 device name was not present when the commands
following mdconfig ran.  Apparently there is the possibility of a delay
between when mdconfig finishes and the names become visible in /dev.
Yes, we could code this better than an unconditional call to "sleep 5"
but IMHO we should fix the underlying problem instead.

MFC after: 3 days

release/sparc64/mkisoimages.sh

@@ -30,6 +30,8 @@ MNT=/mnt
 if [ "x$1" = "x-b" ]; then
 	dd if=/dev/zero of=${IMG} bs=512 count=1024
 	MD=`mdconfig -a -t vnode -f ${IMG}`
+	# XXX - hack to give time for device name to show up
+	sleep 5
 	sunlabel -w -B -b $4/boot/boot1 ${MD} auto
 	newfs -O1 -o space -m 0 /dev/${MD}c
 	mount /dev/${MD}c ${MNT}