Update to the newest gnulib.

diff --git a/gnulib b/gnulib
index 0949c47c03456dae91c15740731b1350296b0497..c893594d0c33139efbc8d75e43eaed487116b58b 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 0949c47c03456dae91c15740731b1350296b0497
+Subproject commit c893594d0c33139efbc8d75e43eaed487116b58b