Avoid overflow in ljpeg_start().
short CLASS guess_byte_order (int words)
{
  uchar test[4][2];
  int t=2, msb;
  double diff, sum[2] = {0,0};

  fread (test[0], 2, 2, ifp);
  for (words-=2; words--; ) {
    fread (test[t], 2, 1, ifp);
    for (msb=0; msb < 2; msb++) {
      diff = (test[t^2][msb] << 8 | test[t^2][!msb])
	   - (test[t  ][msb] << 8 | test[t  ][!msb]);
      sum[msb] += diff*diff;
    }
    t = (t+1) & 3;
  }
  return sum[0] < sum[1] ? 0x4d4d : 0x4949;
}

short CLASS guess_byte_order (int words)
{
  uchar test[4][2];
  int t=2, msb;
  double diff, sum[2] = {0,0};

  fread (test[0], 2, 2, ifp);
  for (words-=2; words--; ) {
    fread (test[t], 2, 1, ifp);
    for (msb=0; msb < 2; msb++) {
      diff = (test[t^2][msb] << 8 | test[t^2][!msb])
	   - (test[t  ][msb] << 8 | test[t  ][!msb]);
      sum[msb] += diff*diff;
    }
    t = (t+1) & 3;
  }
  return sum[0] < sum[1] ? 0x4d4d : 0x4949;
}
