message: Don't use the diff command in regex test
  The output is small enough that getting a pretty diff isn't important.
  In addition this reduces the amount of commands the build system depends
  on.
diff: @@ -169,9 +169,10 @@ const fn jit_bin(config: &'static str, source: &'static str, args: &'static str)
  REGEX.source_dir(&runner.dirs).join("examples").join("regexdna-input.txt"),
  )
  .unwrap();
  - let expected_path =
  - REGEX.source_dir(&runner.dirs).join("examples").join("regexdna-output.txt");
  - let expected = fs::read_to_string(&expected_path).unwrap();
  + let expected = fs::read_to_string(
  + REGEX.source_dir(&runner.dirs).join("examples").join("regexdna-output.txt"),
  + )
  + .unwrap();
  let output = spawn_and_wait_with_input(run_cmd, input);
  // Make sure `[codegen mono items] start` doesn't poison the diff
  @@ -184,20 +185,9 @@ const fn jit_bin(config: &'static str, source: &'static str, args: &'static str)
  let output_matches = expected.lines().eq(output.lines());
  if !output_matches {
  - let res_path = REGEX.source_dir(&runner.dirs).join("res.txt");
  - fs::write(&res_path, &output).unwrap();
  -
  - if cfg!(windows) {
  println!("Output files don't match!");
  println!("Expected Output:\n{}", expected);
  println!("Actual Output:\n{}", output);
  - } else {
  - let mut diff = Command::new("diff");
  - diff.arg("-u");
  - diff.arg(res_path);
  - diff.arg(expected_path);
  - spawn_and_wait(diff);
  - }
  std::process::exit(1);
  }
  