update the header in example/kcf.cpp

modules/tracking/samples/kcf.cpp

@@ -7,8 +7,10 @@
  * example_tracking_kcf faceocc2.webm
  *--------------------------------------------------*/
 
-#include <opencv2/opencv.hpp>
+#include <opencv2/core/utility.hpp>
 #include <opencv2/tracking.hpp>
+#include <opencv2/videoio.hpp>
+#include <opencv2/highgui.hpp>
 #include <iostream>
 #include <cstring>
 #include <algorithm>