Remove portalfs.

While it is a terribly cool idea, it's just awful and since noone has stepped
up to the plate to keep it up with the current vop state, retire it to the
attic.
ok krw@, deraadt@, guenther@, miod@.
comments from jmc@

src/etc/changelist

@@ -1,4 +1,4 @@
-#	$OpenBSD: changelist,v 1.71 2011/01/19 18:34:58 david Exp $
+#	$OpenBSD: changelist,v 1.72 2011/04/05 18:51:25 thib Exp $
 #
 # List of files which the security script backs up and checks
 # for modifications.
@@ -101,7 +101,6 @@
 /etc/pf.conf
 /etc/pf.os
 /etc/pkg.conf
-/etc/portal.conf
 /etc/printcap
 /etc/profile
 /etc/protocols