build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 9d7a6e011389cd02c91194e82d105e0a9698dfbe..d947a2d927b95f33cc35eee0b96d7b46dfc81ecb 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 9d7a6e011389cd02c91194e82d105e0a9698dfbe
+Subproject commit d947a2d927b95f33cc35eee0b96d7b46dfc81ecb