Hmm, should ACL[] be toastable?

I notice that ACL lists are represented as arrays of aclitem, which
means they are now theoretically toastable.  (In practice, I haven't
finished fixing all the routines that touch ACLs, but will soon.)

Do we need long lists of ACLs?  If so, is there any danger in giving
pg_class a toast relation?  It's a tad closer to the heart of the
system than pg_rewrite, so I'm not quite sure if that will work or
not.  Jan?

			regards, tom lane