CLEANUP: stream: don't set ->target to the incoming connection anymore

Now that we have sess->origin to carry that information along, we don't
need to put that into strm->target anymore, so we remove one dependence
on the stream in embryonic connections.
diff --git a/include/types/stream.h b/include/types/stream.h
index 3a0a60f..b83f655 100644
--- a/include/types/stream.h
+++ b/include/types/stream.h
@@ -112,7 +112,7 @@
 struct stream {
 	int flags;                      /* some flags describing the stream */
 	unsigned int uniq_id;           /* unique ID used for the traces */
-	enum obj_type *target;          /* target to use for this stream ; for mini-sess: incoming connection */
+	enum obj_type *target;          /* target to use for this stream */
 
 	struct channel req;             /* request channel */
 	struct channel res;             /* response channel */