The semantic of `-bind` is to restrict the binding only to some address.
If not specified, then the user does not care and we bind to `0.0.0.0`.
If specified then we should honor the restriction and bind only to the specified address.

Before this change, if no `-bind` is given then we would bind to `0.0.0.0:8333` and to `127.0.0.1:8334` (incoming Tor) which is ok - the user does not care to restrict the binding.

However, if only `-bind=addr:port=onion` is given (without ordinary `-bind=`) then we would bind to `addr:port` _and_ to `0.0.0.0:8333` in addition.

Change the above to not do the additional bind: if only
`-bind=addr:port=onion` is given (without ordinary `-bind=`) then bind to `addr:port` (only) and consider incoming connections to that as Tor and do not advertise it. I.e. a Tor-only node.

ninja all check-all