Upgrade libusual

diff --git a/lib b/lib
index af04a5e3f246f70cb49659b6871278b3205f4ffd..9d1ffbb5f4d74ebc35b439686ca10518c8fba2a2 160000 (submodule)
--- a/lib
+++ b/lib
@@ -1 +1 @@
-Subproject commit af04a5e3f246f70cb49659b6871278b3205f4ffd
+Subproject commit 9d1ffbb5f4d74ebc35b439686ca10518c8fba2a2