gnulib: update

diff --git a/gnulib b/gnulib
index ed4e07a077c43052ebb60ea813698f289ba2f367..678815ea7c4d95e04a0fa6d3b491b3c872c677a7 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit ed4e07a077c43052ebb60ea813698f289ba2f367
+Subproject commit 678815ea7c4d95e04a0fa6d3b491b3c872c677a7