message: xtask: Print description for llvm_tools::Error::NotFound
diff: @@ -100,7 +100,14 @@ fn binutil(name: &str) -> Result<PathBuf> {
  let exe = format!("llvm-{name}{exe_suffix}");
  let path = LlvmTools::new()
  - .map_err(|err| anyhow!("{err:?}"))?
  + .map_err(|err| match err {
  + llvm_tools::Error::NotFound => anyhow!(
  + "Could not find llvm-tools component\n\
  + \n\
  + Maybe the rustup component `llvm-tools-preview` is missing? Install it through: `rustup component add llvm-tools-preview`"
  + ),
  + err => anyhow!("{err:?}"),
  + })?
  .tool(&exe)
  .ok_or_else(|| anyhow!("could not find {exe}"))?;
  