message: Correct bencher output format.
diff: @@ -768,7 +768,7 @@ impl Report for BencherReport {
  let unit = formatter.scale_for_machines(&mut values);
  println!(
  - ": {:>11} {}/iter (+/- {})",
  + "bench: {:>11} {}/iter (+/- {})",
  format::integer(values[0]),
  unit,
  format::integer(values[1])
  