message: extend a comment in readlink
diff: @@ -1639,6 +1639,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
  let result = std::fs::read_link(pathname);
  match result {
  Ok(resolved) => {
  + // 'readlink' truncates the resolved path if the provided buffer is not large
  + // enough, and does *not* add a null terminator. That means we cannot use the usual
  + // `write_path_to_c_str` and have to re-implement parts of it ourselves.
  let resolved = this.convert_path_separator(
  Cow::Borrowed(resolved.as_ref()),
  crate::shims::os_str::PathConversion::HostToTarget,
  @@ -1648,8 +1651,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
  if path_bytes.len() > bufsize {
  path_bytes = &path_bytes[..bufsize]
  }
  - // 'readlink' truncates the resolved path if
  - // the provided buffer is not large enough.
  this.write_bytes_ptr(buf, path_bytes.iter().copied())?;
  Ok(path_bytes.len().try_into().unwrap())
  }
  