- Introduce a "struct tcp_addr" which is a lightweight form of struct
   addrinfo for our own internal use.

 - Add a TCP_resolve() function which takes the output from TCP_parse()
   and fills in a list of pointers to struct tcp_addr, one for each
   address returned by getaddrinfo().

 - Modify all TCP_open() callers to use TCP_resolve() and call TCP_open()
   once for every address returned.

 - Add some explanatory comments to tcp.c.


git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@1423 d4fa192b-c00b-0410-8231-f00ffab90ce4