build: fix gnulib build for mingw

Pavel flagged a build regression under mingw, and traced it to a
recent flaw in gnulib for working around nl_langinfo. This picks
up the fix.

* gnulib: Update to latest, for mingw build fixes.

Signed-off-by: Eric Blake <eblake@redhat.com>

diff --git a/.gnulib b/.gnulib
index 9d5efe7d61e1d96a6d7c97ffa4d21c5e33e9bd30..2d280742a9e30088aa169f53353765d5daafe4c0 160000 (submodule)
--- a/.gnulib
+++ b/.gnulib
@@ -1 +1 @@
-Subproject commit 9d5efe7d61e1d96a6d7c97ffa4d21c5e33e9bd30
+Subproject commit 2d280742a9e30088aa169f53353765d5daafe4c0