Update to the newest gnulib.

diff --git a/gnulib b/gnulib
index 3ca749369a314f5fe1e13beb7b6ae068403eee52..981d04f93ea75c85609c18a6dcdb13cce8f07e05 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 3ca749369a314f5fe1e13beb7b6ae068403eee52
+Subproject commit 981d04f93ea75c85609c18a6dcdb13cce8f07e05