Fix unlink(1) for files starting with -
Restore the original behavior of unlink(1), passing the provided filename
directly to unlink(2), handling the first argument being "--" correctly.
This fixes "unlink -foo", broken in r97533.
Submitted by: Brennan Vincent <email@example.com> (original version)
Submitted by: Yuri Pankov
Reported by: Brennan Vincent <firstname.lastname@example.org>
Reviewed by: emaste, kevans, vangyzen, 0mp
Approved by: re (delphij)
Differential Revision: https://reviews.freebsd.org/D17132