Bug#578068: freeciv-server - listen on :: without warning

[Jacob Nevins]

I'd consider this a bug in the clients (all of them) rather than
freeciv-server. As Marko says, if you're running freeciv-server
standalone, you're as likely as not to want other hosts to connect to
it, and if not, you can always specify the "--bind localhost" argument.

I'm looking to make the clients use "--bind localhost" for
client-spawned servers (i.e., single-player games) by default for 2.4.x,
which I think will satisfy the intent of this bug. A trivial patch is in
the upstream bug tracker. Feel free to backport to earlier versions for
Debian if you wish; I'm avoiding doing so upstream primarily due to the
risk of it exposing some platform-dependent networking horror that
completely breaks single-player games.

(I don't think #572990 is relevant here, except tangentially as an
example of the sort of platform-dependence I'm scared of.)