build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 820fa6ad064bf3ba81dc9e2cd7fa2b98bb270902..0481ab52033694e1c137d4911f4d025a186d1a2a 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 820fa6ad064bf3ba81dc9e2cd7fa2b98bb270902
+Subproject commit 0481ab52033694e1c137d4911f4d025a186d1a2a