MINOR: stream: Don't destroy conn-streams but detach app and endp

Don't call cs_destroy() anymore when a stream is released. Instead the
endpoint and the app are detached from the conn-stream.
diff --git a/src/stream.c b/src/stream.c
index 9dbf965..935fce4 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -717,8 +717,10 @@
 	must_free_sess = objt_appctx(sess->origin) && sess->origin == s->csf->end;
 
 	/* FIXME: ATTENTION, si CSF est librérer avant, ça plante !!!! */
-	cs_destroy(s->csb);
-	cs_destroy(s->csf);
+	cs_detach_endp(s->csb);
+	cs_detach_endp(s->csf);
+	cs_detach_app(s->csb);
+	cs_detach_app(s->csf);
 
 	if (must_free_sess) {
 		sess->origin = NULL;