build: fix 'make check' with older git

* .gnulib: Update to latest, for maintainer-makefile fix.
Reported by Matthias Bolte.

diff --git a/.gnulib b/.gnulib
index 54c0573c2f6200b8b9c88a026c7bc8cfe44e0403..2f41af65087fb2460779bc4e7fb62453f79ebae3 160000 (submodule)
--- a/.gnulib
+++ b/.gnulib
@@ -1 +1 @@
-Subproject commit 54c0573c2f6200b8b9c88a026c7bc8cfe44e0403
+Subproject commit 2f41af65087fb2460779bc4e7fb62453f79ebae3