message: dedup code a bit
diff: @@ -25,8 +25,9 @@ fn rustc_lib_path() -> PathBuf {
  }
  fn run_tests(mode: &str, path: &str, target: &str, mut flags: Vec<String>) {
  - // Some flags we always want.
  - if rustc_test_suite().is_none() {
  + let in_rustc_test_suite = rustc_test_suite().is_some();
  + // Add some flags we always want.
  + if !in_rustc_test_suite {
  // Only `-Dwarnings` on the Miri side to make the rustc toolstate management less painful.
  // (We often get warnings when e.g. a feature gets stabilized or some lint gets added/improved.)
  flags.push("-Dwarnings -Dunused".to_owned()); // overwrite the -Aunused in compiletest-rs
  @@ -40,7 +41,7 @@ fn run_tests(mode: &str, path: &str, target: &str, mut flags: Vec<String>) {
  let mut config = compiletest::Config::default().tempdir();
  config.mode = mode.parse().expect("Invalid mode");
  config.rustc_path = miri_path();
  - if rustc_test_suite().is_some() {
  + if in_rustc_test_suite {
  config.run_lib_path = rustc_lib_path();
  config.compile_lib_path = rustc_lib_path();
  }
  