Update to the newest gnulib.

diff --git a/gnulib b/gnulib
index 564afbf88812844f83589d091bff88af55556de6..4ad699672ce46009832793ecd8aa4027bd10205e 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 564afbf88812844f83589d091bff88af55556de6
+Subproject commit 4ad699672ce46009832793ecd8aa4027bd10205e