build: update gnulib to latest

diff --git a/gnulib b/gnulib
index 11e7f89e5fcfc612d522d7b0c73994c9222644c5..594d9876806a796e669d08730dab03b6bfedb29a 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 11e7f89e5fcfc612d522d7b0c73994c9222644c5
+Subproject commit 594d9876806a796e669d08730dab03b6bfedb29a