Update to newest gnulib.

diff --git a/gnulib b/gnulib
index a4398f60f17e3de5463540311bd6bc5c33045822..5b891d3d9e310d4faa175f3a97921c466c907ba1 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit a4398f60f17e3de5463540311bd6bc5c33045822
+Subproject commit 5b891d3d9e310d4faa175f3a97921c466c907ba1