the local socket address in the SessionOpen records in SHM.

This costs us an extra getsockname(2) call per connection, so default
to off.

SHM clients can tell the state of this option by the number of fields
in SessionOpen: 3 (off) or 4 (on).



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@2745 d4fa192b-c00b-0410-8231-f00ffab90ce4