External zones don't need split-brain madness any more.

External zones don't need split-brain madness any more.

They used to require it when I didn't have a proper publicly routable
border network for the servers.  So only generate `outside' views for
external zones.  This also means I have to swap around the
`preferred-subnet-case' for choosing server addresses to favour
outside, but I think that's the right answer anyway.