Update interface.

diff --git a/interface b/interface
index 1198dd741e1d7dd0c6a5391a76caf5df3297a8e0..f21ffa4ce6e35af6fa6c318971c7a58719b4c524 160000 (submodule)
--- a/interface
+++ b/interface
@@ -1 +1 @@
-Subproject commit 1198dd741e1d7dd0c6a5391a76caf5df3297a8e0
+Subproject commit f21ffa4ce6e35af6fa6c318971c7a58719b4c524