build: ensure AT_NO_AUTOMOUNT is defined

update gnulib submodule to latest,
where this is the only change

diff --git a/gnulib b/gnulib
index 23cca8268d21f5d58ed0209002d5673d0518c426..a2735049fd84b3ec0cae33c020459995cc7e678f 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 23cca8268d21f5d58ed0209002d5673d0518c426
+Subproject commit a2735049fd84b3ec0cae33c020459995cc7e678f