bridges distinguish themselves in the netinfo cell

When a bridge crafts its netinfo cell in connection_or_send_netinfo(), it includes its addr, since router_get_my_routerinfo() returns non-NULL.

For incoming OR connections, that's fine and good. But for outgoing OR connections, it should be acting like a client instead.

Reported by our friendly bug reporter "troll_un".

(We could fix in 0.2.2, but since some of our bridge enumeration fixes aren't going into 0.2.2, I don't think this one needs to either.)