Build tutorial codes together with other samples

These codes should be included into regular builds.

samples/cpp/tutorial_code/features2D/SURF_detector.cpp

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