Tweak benchmark harness.
Tweak benchmark harness.

This makes it so passing -h or --help works as expected.

rust-lang/regex,rust-lang/regex,SeanRBurton/regex,golddranks/regex,golddranks/regex,rust-lang-nursery/regex,SeanRBurton/regex,rust-lang-nursery/regex,rust-lang/regex,rust-lang-nursery/regex,SeanRBurton/regex,rust-lang-nursery/regex,SeanRBurton/regex,rust-lang-nursery/regex,golddranks/regex,rust-lang/regex,rust-lang/regex,SeanRBurton/regex