[BUG] buffers: remove BF_MAY_CONNECT and fix forwarding issue

It wasn't really wise to separate BF_MAY_CONNECT and BF_MAY_FORWARD,
as it caused trouble in TCP mode because the connection was allowed
but not the forwarding. Remove BF_MAY_CONNECT.
diff --git a/src/client.c b/src/client.c
index 77b1d96..7135d71 100644
--- a/src/client.c
+++ b/src/client.c
@@ -338,7 +338,7 @@
 			s->req->rlim -= MAXREWRITE;
 
 		if (!(s->analysis & AN_REQ_ANY))
-			s->req->flags |= BF_MAY_CONNECT;  /* don't wait to establish connection */
+			s->req->flags |= BF_MAY_FORWARD;  /* don't wait to establish connection */
 
 		s->req->rto = s->fe->timeout.client;
 		s->req->wto = s->be->timeout.server;