Implement a quick and dirty fallback to secondary addresses for multihomed servers. This implementation matches how http libraries like neon and curl handle this.
Implement a quick and dirty fallback to secondary addresses for multihomed
servers. This implementation matches how http libraries like neon and curl
handle this.

Current webbrowsers have smarter algorithms to hide ipv6 problems from
their users, by initiating multiple connections, asynchronous resolving, etc.
Recent IETF reports recommend against agressively preferring ipv4 over
ipv6 and recommend a quick fallback instead, although with a lower timeout
than the default +- 20 seconds.

* outgoing.c
  (serf__process_connection): Handle the common connection errors as trigger
    to retry the connection on the next address.

jandre/serf,jandre/serf,jandre/serf,jandre/serf