build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 0173b1e598b66fc95f4cf3af023313e29701e384..1b712ba8bb1359974aa495a1a95b2185ed68e87e 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 0173b1e598b66fc95f4cf3af023313e29701e384
+Subproject commit 1b712ba8bb1359974aa495a1a95b2185ed68e87e