Update to newest gnulib.

diff --git a/gnulib b/gnulib
index f6225ebbe70d592453edcb47f9238eb4336edca9..ab5b2560b129ae8dc939d79d0be4af6b5ec46885 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit f6225ebbe70d592453edcb47f9238eb4336edca9
+Subproject commit ab5b2560b129ae8dc939d79d0be4af6b5ec46885