build: update gnulib submodule to latest

To fix a syntax-check false failure

diff --git a/gnulib b/gnulib
index 69822de4243b40e1da10046e1c12e79703ea9a7d..a3e1e74e65af0649224d84813df2e9ebea2e9a67 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 69822de4243b40e1da10046e1c12e79703ea9a7d
+Subproject commit a3e1e74e65af0649224d84813df2e9ebea2e9a67