jpag图片DCT的改进，改进后比传统加速快200倍以上-Improve the jpag s DCT

libjpeg的加速版本，一般情况下，保存500万像素的影像turbo版本的库要快上2倍以上-accelerated version of libjpeg, under normal circumstances, to save five million pixel image turbo version of the library more than 2 times faster