init: populate /etc/conf/idunn to be used by resume and friends

initramfs/init.sh

@@ -52,6 +52,12 @@ for x in USR1 USR2 TERM INT; do
 	trap "shutoff_handler $x" $x
 done
 
+cat > /etc/conf/idunn <<EOT
+root="$root"
+init="${init:-/sbin/init}"
+initopt="$*"
+EOT
+
 # start the world
 /etc/rc.d/rc.sysinit 2>&1 | tee -a $LOG