routing (-V option to vnodesetup).  I was going to do this just for
jails that used gated, but there is no efficient way to do this
(I don't want to make a redundent "tmcc routing" call for every jail
just for the very rare case they are using gated).

Since it is the Right Thing To Do anyway, I'll just go for it now
while we only have one external user.

There is a possibility of unexpected consequences on mini, but I'll
cross that bridge when I get to it (or more likely, when Leigh gets
to it :-)