update vkh with cstdio include

diff --git a/vkh b/vkh
index bede6aeb4264040784a422e64796ce21a012eab5..18059c4c6464ff13ffb6764c8a882cf66d0676f5 160000 (submodule)
--- a/vkh
+++ b/vkh
@@ -1 +1 @@
-Subproject commit bede6aeb4264040784a422e64796ce21a012eab5
+Subproject commit 18059c4c6464ff13ffb6764c8a882cf66d0676f5