update vkh

diff --git a/vkh b/vkh
index 61930b1e9ec4ce9b95ea0e4dd02d9a3e530a312b..81a2e16cd59e608be7f840a2123fcdd36eed6e62 160000 (submodule)
--- a/vkh
+++ b/vkh
@@ -1 +1 @@
-Subproject commit 61930b1e9ec4ce9b95ea0e4dd02d9a3e530a312b
+Subproject commit 81a2e16cd59e608be7f840a2123fcdd36eed6e62