build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index c96bab3fee48a9df55e7366344f838e1fc785c28..da8d59ee79138b85daee1ad5b22ea12e4fb6ce47 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit c96bab3fee48a9df55e7366344f838e1fc785c28
+Subproject commit da8d59ee79138b85daee1ad5b22ea12e4fb6ce47