Update to newest gnulib.

diff --git a/gnulib b/gnulib
index 5fc612b722cd22c7f84a7d9aac9bb01035a869be..dce8759f0f0236a860a3e68b63c5e99cc6f168f9 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 5fc612b722cd22c7f84a7d9aac9bb01035a869be
+Subproject commit dce8759f0f0236a860a3e68b63c5e99cc6f168f9