Update to latest gnulib with new copyright year.
Run "make update-copyright" and then...
* gnulib: Update included in this commit as copyright years
are the only change from the previous gnulib commit.
* tests/init.sh: Sync with gnulib to pick up copyright year.
* bootstrap: Manually update copyright year,
until we fully sync with gnulib at a later stage.
* tests/sample-test: Adjust to use the single most recent year.
* tests/split/l-chunk.sh: Move the "expensive" portion to ...
* tests/split/l-chunk-root.sh: .. A new test split from l-chunk.sh
which uses an isolated TMPDIR, rather than exhausting /tmp,
as that gives false positive failures with some other coreutils tests
like tac-2-nonseekable.sh and shuf-reservoir.sh at least.
* tests/local.mk: Reference the new test.
