maint: update to latest gnulib

Fix mingw build regarding rpl_{printf,scanf} symbols.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>

diff --git a/.gnulib b/.gnulib
index 246b3b28808ee5f4664be674dce573af9497fc7a..68b6adebef05670a312fb92b05e7bd089d2ed43a 160000 (submodule)
--- a/.gnulib
+++ b/.gnulib
@@ -1 +1 @@
-Subproject commit 246b3b28808ee5f4664be674dce573af9497fc7a
+Subproject commit 68b6adebef05670a312fb92b05e7bd089d2ed43a