message: fix conditional compilation condition for os_str <-> bytes conversion
diff: @@ -463,11 +463,11 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
  'tcx: 'a,
  'mir: 'a,
  {
  - #[cfg(target_os = "unix")]
  + #[cfg(unix)]
  fn bytes_to_os_str<'tcx, 'a>(bytes: &'a [u8]) -> InterpResult<'tcx, &'a OsStr> {
  - Ok(std::os::unix::ffi::OsStringExt::from_bytes(bytes))
  + Ok(std::os::unix::ffi::OsStrExt::from_bytes(bytes))
  }
  - #[cfg(not(target_os = "unix"))]
  + #[cfg(not(unix))]
  fn bytes_to_os_str<'tcx, 'a>(bytes: &'a [u8]) -> InterpResult<'tcx, &'a OsStr> {
  let s = std::str::from_utf8(bytes)
  .map_err(|_| err_unsup_format!("{:?} is not a valid utf-8 string", bytes))?;
  @@ -490,11 +490,11 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
  scalar: Scalar<Tag>,
  size: u64,
  ) -> InterpResult<'tcx, (bool, u64)> {
  - #[cfg(target_os = "unix")]
  + #[cfg(unix)]
  fn os_str_to_bytes<'tcx, 'a>(os_str: &'a OsStr) -> InterpResult<'tcx, &'a [u8]> {
  - std::os::unix::ffi::OsStringExt::into_bytes(os_str)
  + Ok(std::os::unix::ffi::OsStrExt::as_bytes(os_str))
  }
  - #[cfg(not(target_os = "unix"))]
  + #[cfg(not(unix))]
  fn os_str_to_bytes<'tcx, 'a>(os_str: &'a OsStr) -> InterpResult<'tcx, &'a [u8]> {
  // On non-unix platforms the best we can do to transform bytes from/to OS strings is to do the
  // intermediate transformation into strings. Which invalidates non-utf8 paths that are actually
  