:art: use some int_fast

diff --git a/util b/util
index b4e733a3fc7c8fdbd3bd96e768f815d7a1aa6b7c..dd768c3b087efa01fe78b7f9a71158180fadf86a 160000 (submodule)
--- a/util
+++ b/util
@@ -1 +1 @@
-Subproject commit b4e733a3fc7c8fdbd3bd96e768f815d7a1aa6b7c
+Subproject commit dd768c3b087efa01fe78b7f9a71158180fadf86a