message: Error with EINVAL on unsupported `whence` argument
diff: @@ -285,7 +285,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
  } else if whence == this.eval_libc_i32("SEEK_END")? {
  SeekFrom::End(offset)
  } else {
  - throw_unsup_format!("Unsupported whence argument to lseek64: {}", whence)
  + let einval = this.eval_libc("EINVAL")?;
  + this.set_last_error(einval)?;
  + return Ok(-1);
  };
  if let Some(handle) = this.machine.file_handler.handles.get_mut(&fd) {
  