build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 3e00f5fce5b904dc642aff88abbcf75867263e0a..6038ee4b827caaf05fa37dbb2304fedb9d0cd6c7 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 3e00f5fce5b904dc642aff88abbcf75867263e0a
+Subproject commit 6038ee4b827caaf05fa37dbb2304fedb9d0cd6c7