Update to newest gnulib.

diff --git a/gnulib b/gnulib
index 6642aeb47aee3d82978a27497dc9ca57058c66b4..5fc612b722cd22c7f84a7d9aac9bb01035a869be 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 6642aeb47aee3d82978a27497dc9ca57058c66b4
+Subproject commit 5fc612b722cd22c7f84a7d9aac9bb01035a869be