build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 2d386f229aba9ecda85736b931e2964d7922d90e..cd7fa0904bb6efb451ecc25907077fcfdf031824 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 2d386f229aba9ecda85736b931e2964d7922d90e
+Subproject commit cd7fa0904bb6efb451ecc25907077fcfdf031824