build: update gnulib for more openat changes

diff --git a/gnulib b/gnulib
index 908ae019f6ba87eaec0f6dd16cb4e62d5fc08789..667561d720dd1e22b51fe5d308a8f94d49d46b85 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 908ae019f6ba87eaec0f6dd16cb4e62d5fc08789
+Subproject commit 667561d720dd1e22b51fe5d308a8f94d49d46b85