[MEDIUM] move QUEUE and TAR timers to stream interfaces

It was not practical to have QUEUE and TAR timers in buffers, as they caused
triggering of the timeout flags. Move them to the stream interface where they
belong.
diff --git a/src/backend.c b/src/backend.c
index 16b2cc9..4d855db 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -1997,7 +1997,7 @@
 		return 1;
 
 	case SRV_STATUS_QUEUED:
-		t->req->wex = tick_add_ifset(now_ms, t->be->timeout.queue);
+		t->req->cons->exp = tick_add_ifset(now_ms, t->be->timeout.queue);
 		t->req->cons->state = SI_ST_QUE;
 		/* do nothing else and do not wake any other session up */
 		return 1;