Update to the newest gnulib.

diff --git a/gnulib b/gnulib
index 979dcc75b404ed579e588e048a13145f04440e15..4dcbda874f6e95f8f12d8721d6defa1428af2b6b 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 979dcc75b404ed579e588e048a13145f04440e15
+Subproject commit 4dcbda874f6e95f8f12d8721d6defa1428af2b6b