build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index d268b4b9646954b4a3b27fa924cf217b09e5acc1..dbd5c0e936cc56b4572b029273118892c64a5cdc 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit d268b4b9646954b4a3b27fa924cf217b09e5acc1
+Subproject commit dbd5c0e936cc56b4572b029273118892c64a5cdc