message: Update for cranelift change
diff: pub struct CommentWriter(pub HashMap<Inst, String>);
  impl FuncWriter for CommentWriter {
  + fn write_preamble(
  + &mut self,
  + w: &mut dyn fmt::Write,
  + func: &Function,
  + reg_info: Option<&isa::RegInfo>,
  + ) -> Result<bool, fmt::Error> {
  + PlainWriter.write_preamble(w, func, reg_info)
  + }
  +
  + fn write_ebb_header(
  + &mut self,
  + w: &mut dyn fmt::Write,
  + func: &Function,
  + isa: Option<&dyn isa::TargetIsa>,
  + ebb: Ebb,
  + indent: usize,
  + ) -> fmt::Result {
  + PlainWriter.write_ebb_header(w, func, isa, ebb, indent)
  + }
  +
  fn write_instruction(
  &mut self,
  w: &mut dyn fmt::Write,
  @@ -25,15 +45,6 @@ fn write_instruction(
  }
  Ok(())
  }
  -
  - fn write_preamble(
  - &mut self,
  - w: &mut dyn fmt::Write,
  - func: &Function,
  - reg_info: Option<&isa::RegInfo>,
  - ) -> Result<bool, fmt::Error> {
  - PlainWriter.write_preamble(w, func, reg_info)
  - }
  }
  impl<'a, 'tcx: 'a, B: Backend + 'a> FunctionCx<'a, 'tcx, B> {
  