message: whitelist platforms where panicking should work
diff: @@ -132,6 +132,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
  // This matches calls to the foreign item `panic_impl`.
  // The implementation is provided by the function with the `#[panic_handler]` attribute.
  "panic_impl" => {
  + // Make sure panicking actually works on this platform.
  + match this.tcx.sess.target.target.target_os.as_str() {
  + "linux" | "macos" => {},
  + _ => throw_unsup_format!("panicking is not supported on this platform"),
  + }
  +
  let panic_impl_id = this.tcx.lang_items().panic_impl().unwrap();
  let panic_impl_instance = ty::Instance::mono(*this.tcx, panic_impl_id);
  return Ok(Some(&*this.load_mir(panic_impl_instance.def, None)?));
  