Update to the newest gnulib.

diff --git a/gnulib b/gnulib
index 6542d39be48065193e9c64dcb6eb0d854a1242dc..9187f1c193767b7a09a2d9ef8e72f6f0dabd3250 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 6542d39be48065193e9c64dcb6eb0d854a1242dc
+Subproject commit 9187f1c193767b7a09a2d9ef8e72f6f0dabd3250