build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index c46ae39631773a7fdae7d171cc4ef0bf2123efff..d4356ced2b562ac55101ab23a5321114c41e0eda 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit c46ae39631773a7fdae7d171cc4ef0bf2123efff
+Subproject commit d4356ced2b562ac55101ab23a5321114c41e0eda