build: update gnulib for fixed maint.mk

diff --git a/gnulib b/gnulib
index 3a4836d1fa061adf7b2f96fbda9c2345e6210732..5eae670f051c94b73d7dd6aae2d4a814ca691f9e 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 3a4836d1fa061adf7b2f96fbda9c2345e6210732
+Subproject commit 5eae670f051c94b73d7dd6aae2d4a814ca691f9e