Add the first stab at a "restart" mechanism.

Add the first stab at a "restart" mechanism.

The intent is to be able to do things like:

	backend b1 {
		set backend.host = "fs.freebsd.dk";
		set backend.port = "82";
	}
	backend b2 {
		set backend.host = "fs.freebsd.dk";
		set backend.port = "81";
	}
	backend b3 {
		set backend.host = "fs.freebsd.dk";
		set backend.port = "80";
	}

	sub vcl_recv {
		remove req.http.cookie;
		if (req.restarts == 0) {
			set req.backend = b1;
		} else if (req.restarts == 1) {
			set req.backend = b2;
		} else {
			set req.backend = b3;
		}
	}

	sub vcl_fetch {
		if (obj.status != 200) {
			restart;
		}
	}

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@2067 d4fa192b-c00b-0410-8231-f00ffab90ce4