build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 2ef6006ffc4080cf8c0c1f4d4deeb4c357d7a695..9cde39f881204e422d4bdad67ab12877d6a8172d 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 2ef6006ffc4080cf8c0c1f4d4deeb4c357d7a695
+Subproject commit 9cde39f881204e422d4bdad67ab12877d6a8172d