add ramdisk target, very basic, unused atm, but makes regress happy

src/etc/etc.sun3/MAKEDEV.md

@@ -1,5 +1,5 @@
 vers(__file__,
-	{-$OpenBSD: MAKEDEV.md,v 1.2 2002/02/14 13:29:21 todd Exp $-},
+	{-$OpenBSD: MAKEDEV.md,v 1.3 2002/02/21 13:09:03 todd Exp $-},
 etc.MACHINE)dnl
 dnl
 dnl Copyright (c) 2001 Todd T. Fries <todd@OpenBSD.org>
@@ -69,6 +69,9 @@ test -d /usr/etc && PATH=$PATH:/usr/etc
 dnl
 divert(7)dnl
 dnl
+ramdisk)
+	R std random bpf0 sd0 sd1 rd0
+	;;
 _std(2, 3, 37, 7, 16)
 	M kd		c 1 0 600
 	M eeprom	c 3 11 640 kmem