Update to the newest gnulib.

diff --git a/gnulib b/gnulib
index 2529243503f93aed2ddb249e4b459c5afda78add..efa78d8905e1a0260930692fd888d1917a837cd6 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 2529243503f93aed2ddb249e4b459c5afda78add
+Subproject commit efa78d8905e1a0260930692fd888d1917a837cd6