Upgrade libusual

diff --git a/lib b/lib
index a8667935819d50719c7f049206418e9f07e447d0..b3b239063d054cfdc6ea1f3602de92c90bdc8977 160000 (submodule)
--- a/lib
+++ b/lib
@@ -1 +1 @@
-Subproject commit a8667935819d50719c7f049206418e9f07e447d0
+Subproject commit b3b239063d054cfdc6ea1f3602de92c90bdc8977