Update to the newest gnulib.

diff --git a/gnulib b/gnulib
index bb3fd10e6309f017618a12b2c10d3bfb813bfc08..6cac6f014973dce669f9fa50cce7540eda711050 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit bb3fd10e6309f017618a12b2c10d3bfb813bfc08
+Subproject commit 6cac6f014973dce669f9fa50cce7540eda711050