Update samples/cpp/tutorial_code/features2D/SURF_detector.cpp

Changes made for OpenCV 2.4.2 compatibility

samples/cpp/tutorial_code/features2D/SURF_FlannMatcher.cpp

@@ -9,6 +9,7 @@
 #include "opencv2/core/core.hpp"
 #include "opencv2/features2d/features2d.hpp"
 #include "opencv2/highgui/highgui.hpp"
+#include "opencv2/nonfree/features2d.hpp"
 
 using namespace cv;