[move sift.cpp] xfeatures2d: apply CV_OVERRIDE/CV_FINAL
[move sift.cpp] xfeatures2d: apply CV_OVERRIDE/CV_FINAL

original commit: https://github.com/opencv/opencv_contrib/commit/ec65e5b29c1c4928aee3d56a44bb399d4af6b61a

opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv