[vty] ensure we mark fd in writefd once we vty_out() something
diff --git a/openbsc/src/vty/vty.c b/openbsc/src/vty/vty.c
index affe28d..788c7fd 100644
--- a/openbsc/src/vty/vty.c
+++ b/openbsc/src/vty/vty.c
@@ -236,6 +236,8 @@
 			talloc_free(p);
 	}
 
+	vty_event(VTY_WRITE, vty->fd, vty);
+
 	return len;
 }