refresh libusual

diff --git a/lib b/lib
index 8d04ff2e59f919d58549c8f8faaa56d3d876efc7..6c0a3841b5fa5c689318e84be65e0402533ef7d1 160000 (submodule)
--- a/lib
+++ b/lib
@@ -1 +1 @@
-Subproject commit 8d04ff2e59f919d58549c8f8faaa56d3d876efc7
+Subproject commit 6c0a3841b5fa5c689318e84be65e0402533ef7d1