Updated with comments of speclad

modules/contrib/CMakeLists.txt

-ocv_define_module(contrib opencv_imgproc opencv_calib3d opencv_features2d opencv_ml opencv_video opencv_objdetect opencv_nonfree OPTIONAL opencv_highgui)
+ocv_define_module(contrib opencv_imgproc opencv_calib3d opencv_features2d opencv_ml opencv_video opencv_objdetect OPTIONAL opencv_highgui opencv_nonfree)

modules/contrib/src/featuretracker.cpp

@@ -45,6 +45,12 @@
 #include "opencv2/calib3d/calib3d.hpp"
 #include "opencv2/contrib/hybridtracker.hpp"
 
+#ifdef HAVE_OPENCV_NONFREE
+#include "opencv2/nonfree/nonfree.hpp"
+
+static bool makeUseOfNonfree = initModule_nonfree();
+#endif
+
 using namespace cv;
 
 CvFeatureTracker::CvFeatureTracker(CvFeatureTrackerParams _params) :