added opencv_flann to pkg-config script for opencv
added opencv_flann to pkg-config script for opencv

opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,apavlenko/opencv,apavlenko/opencv,apavlenko/opencv,opencv/opencv,apavlenko/opencv,opencv/opencv,apavlenko/opencv,opencv/opencv,apavlenko/opencv,opencv/opencv