MINOR: hlua: Always access the stream-int via the conn-stream

To be able to move the stream-interface from the stream to the conn-stream,
all access to the SI is done via the conn-stream. This patch is limited to
the hlua part.
diff --git a/src/hlua.c b/src/hlua.c
index cc7a585..a6cc839 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -2794,8 +2794,8 @@
 	/* inform the stream that we want to be notified whenever the
 	 * connection completes.
 	 */
-	si_cant_get(&s->si[0]);
-	si_rx_endp_more(&s->si[0]);
+	si_cant_get(cs_si(s->csf));
+	si_rx_endp_more(cs_si(s->csf));
 	appctx_wakeup(appctx);
 
 	hlua->gc_count++;