Upgrade libusual

Mainly to get OpenSSL 1.1 fixes

Fixes: #159

diff --git a/lib b/lib
index ab4f9b547919a22c32ef9e2c7e3925c374b17ecf..af04a5e3f246f70cb49659b6871278b3205f4ffd 160000 (submodule)
--- a/lib
+++ b/lib
@@ -1 +1 @@
-Subproject commit ab4f9b547919a22c32ef9e2c7e3925c374b17ecf
+Subproject commit af04a5e3f246f70cb49659b6871278b3205f4ffd