new branch in gnulib: coreutils-8.9

[Jim Meyering]

In releasing coreutils-8.9, I left its gnulib submodule pointing at a
private commit that was going to be pushed, pending an ACK...  Since a
slightly different commit was pushed, coreutils' submodule SHA1 was
invalid for a short interval.  However, I have pushed my local commit
to the new gnulib branch named "coreutils-8.9".  With that, anyone
cloning coreutils and trying to build from the 8.9 tag *will* get a
usable gnulib hierarchy.

Thanks to Eric Blake for noticing so quickly and for the suggestion
to push my commit to a branch in gnulib.