build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 4b60490554dbc981f15d46976cb0e74faba707d0..d52f9c5197805e44c867819c2f1a4e1b4a195740 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 4b60490554dbc981f15d46976cb0e74faba707d0
+Subproject commit d52f9c5197805e44c867819c2f1a4e1b4a195740