update vkh (fallback present mode log)

diff --git a/vkh b/vkh
index 87e1a713755fd58e2bb2e47af9568583ed99d8dd..16fb9a9fa03fb4666f1ba7c5d81f84d568cf032a 160000 (submodule)
--- a/vkh
+++ b/vkh
@@ -1 +1 @@
-Subproject commit 87e1a713755fd58e2bb2e47af9568583ed99d8dd
+Subproject commit 16fb9a9fa03fb4666f1ba7c5d81f84d568cf032a