message: update comment re: not using higher mir-opt-level
diff: @@ -66,9 +66,8 @@ fn compile_fail(path: &str, target: &str, opt: bool) {
  let mut flags = Vec::new();
  if opt {
  - // Optimizing too aggressivley makes UB detection harder, but test at least
  - // the default value.
  - // FIXME: Opt level 3 ICEs during stack trace generation.
  + // FIXME: Opt level 2 ICEs during stack trace generation.
  + // See https://github.com/rust-lang/rust/issues/66077.
  flags.push("-Zmir-opt-level=1".to_owned());
  }
  