[MEDIUM] buffers: add BF_READ_ATTACHED and BF_ANA_TIMEOUT

Those two flags will be used to wake up analysers only when
needed.
diff --git a/src/proto_http.c b/src/proto_http.c
index b32c042..31c9879 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -869,8 +869,8 @@
 		if (s->req->cons->state == SI_ST_EST)
 			stream_sock_data_finish(s->req->cons->fd);
 
-		s->req->flags &= BF_CLEAR_READ & BF_CLEAR_WRITE;
-		s->rep->flags &= BF_CLEAR_READ & BF_CLEAR_WRITE;
+		s->req->flags &= BF_CLEAR_READ & BF_CLEAR_WRITE & BF_CLEAR_TIMEOUT;
+		s->rep->flags &= BF_CLEAR_READ & BF_CLEAR_WRITE & BF_CLEAR_TIMEOUT;
 		s->si[0].prev_state = s->si[0].state;
 		s->si[1].prev_state = s->si[1].state;
 
@@ -3683,8 +3683,7 @@
 			 */
 		}
 
-		if (!rep->analysers)
-			buffer_write_ena(t->rep);
+		rep->flags |= BF_READ_ATTACHED; /* producer is now attached */
 		req->wex = TICK_ETERNITY;
 		return 0;
 	}