Update to the newest gnulib.

diff --git a/gnulib b/gnulib
index 6cac6f014973dce669f9fa50cce7540eda711050..a9447b51ea6d87507b1e853023c7adc428267ece 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 6cac6f014973dce669f9fa50cce7540eda711050
+Subproject commit a9447b51ea6d87507b1e853023c7adc428267ece