yes: Completely overengineer

If we're going to overengineer this, we may as well go all the way.

• If multiple arguments are given, concatenate them into a space- separated list like GNU coreutils does.

• When duplicating the expletive, do so exponentially.

• Most importantly, don't modify the memory that argv points to.

MFC after: 1 week
Sponsored by: Klara, Inc.
Reviewed by: kevans, allanjude
Differential Revision: https://reviews.freebsd.org/D55617