od: skip past end of seekable inputs without error

[sylvestre]

fixes: tests/od/od-j

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/date/date-locale-hour (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tail/retry (fails in this run but passes in the 'main' branch)
Congrats! The gnu test tests/od/od-j is no longer failing!
Note: The gnu test tests/tail/tail-n0f is now being skipped but was previously passing.
Congrats! The gnu test tests/cp/link-heap is now passing!
Congrats! The gnu test tests/tail/pipe-f is now passing!