revert to previous working version of gnulib

This reverts commit 0c31cdc2d13a1e47106ce708ca9c94df8d21f764.

diff --git a/gnulib b/gnulib
index 3c6b938cb0b5c4155b0254ae0406a6789c1efbcf..80cd995cdcbf4b9ded895a43621a11f11806ad8d 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 3c6b938cb0b5c4155b0254ae0406a6789c1efbcf
+Subproject commit 80cd995cdcbf4b9ded895a43621a11f11806ad8d