Update to newest gnulib.

diff --git a/gnulib b/gnulib
index cf9faba87af1487f8e8920947a8e45d45e2512d5..478a626cc68430e9db0ebd19166a28eb30ed431b 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit cf9faba87af1487f8e8920947a8e45d45e2512d5
+Subproject commit 478a626cc68430e9db0ebd19166a28eb30ed431b