build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 6bb58afd0e0c21a5260a3a5b4a2dc94e8e2e2a6d..948ba80168293e3d8a905eeffb0ab61424c4c374 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 6bb58afd0e0c21a5260a3a5b4a2dc94e8e2e2a6d
+Subproject commit 948ba80168293e3d8a905eeffb0ab61424c4c374