MINOR: sink: 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 sink part.
diff --git a/src/sink.c b/src/sink.c
index b09b895..7a4751b 100644
--- a/src/sink.c
+++ b/src/sink.c
@@ -668,10 +668,10 @@
 
 
 	s->target = &sft->srv->obj_type;
-	if (!sockaddr_alloc(&s->si[1].dst, &sft->srv->addr, sizeof(sft->srv->addr)))
+	if (!sockaddr_alloc(&cs_si(s->csb)->dst, &sft->srv->addr, sizeof(sft->srv->addr)))
 		goto out_free_strm;
 	s->flags = SF_ASSIGNED|SF_ADDR_SET;
-	s->si[1].flags |= SI_FL_NOLINGER;
+	cs_si(s->csb)->flags |= SI_FL_NOLINGER;
 
 	s->do_log = NULL;
 	s->uniq_id = 0;