BUG/MEDIUM: stream: don't automatically forward connect nor close

Upon stream instanciation, we used to enable channel auto connect
and auto close to ease TCP processing. But commit 9aaf778 ("MAJOR:
connection : Split struct connection into struct connection and
struct conn_stream.") has revealed that it was a bad idea because
this commit enables reading of the trailing shutdown that may follow
a small requests, resulting in a read and a shutr turned into shutw
before the stream even has a chance to apply the filters. This
causes an issue with impossible situations where the backend stream
interface is still in SI_ST_INI with a closed output, which blocks
some streams for example when performing a redirect with filters
enabled.

Let's change this so that we only enable these two flags if there is
no analyser on the stream. This way process_stream() has a chance to
let the analysers decide whether or not to allow the shutdown event
to be transferred to the other side.

It doesn't seem possible to trigger this issue before 1.8, so for now
it is preferable not to backport this fix.

src/stream.c

@@ -224,8 +224,11 @@ struct stream *stream_new(struct session *sess, enum obj_type *origin)
 	channel_init(&s->req);
 	s->req.flags |= CF_READ_ATTACHED; /* the producer is already connected */
 	s->req.analysers = sess->listener ? sess->listener->analysers : 0;
+
+	if (!sess->fe->fe_req_ana) {
 		channel_auto_connect(&s->req);  /* don't wait to establish connection */
 		channel_auto_close(&s->req);    /* let the producer forward close requests */
+	}
 
 	s->req.rto = sess->fe->timeout.client;
 	s->req.wto = TICK_ETERNITY;