xfeatures2d

代码说明：

说明：  添加opencv最新库中以来的xfeatured下载文件，cmake使用(Add the xfeatured download file from opencv's latest library, and cmake uses it)

文件列表：

xfeatures2d
xfeatures2d\boostdesc_bgm.i
xfeatures2d\boostdesc_bgm_bi.i
xfeatures2d\boostdesc_bgm_hd.i
xfeatures2d\boostdesc_binboost_064.i
xfeatures2d\boostdesc_binboost_128.i
xfeatures2d\boostdesc_binboost_256.i
xfeatures2d\boostdesc_lbgm.i
xfeatures2d\vgg_generated_120.i
xfeatures2d\vgg_generated_48.i
xfeatures2d\vgg_generated_64.i
xfeatures2d\vgg_generated_80.i