Upgrade libusual to get portability fixes.

Should be safe as no existing modules have big changes.

diff --git a/lib b/lib
index 7dd946ae6023574eefdb9d254faae46805c16c07..d3b909223fc70fb05d1baf3976494ef553bde25f 160000 (submodule)
--- a/lib
+++ b/lib
@@ -1 +1 @@
-Subproject commit 7dd946ae6023574eefdb9d254faae46805c16c07
+Subproject commit d3b909223fc70fb05d1baf3976494ef553bde25f