adapted all nonfree header inclusion since it doesn't exist anymore as a module

samples/gpu/surf_keypoint_matcher.cpp

@@ -2,13 +2,13 @@
 
 #include "opencv2/opencv_modules.hpp"
 
-#ifdef HAVE_OPENCV_NONFREE
+#ifdef HAVE_OPENCV_XFEATURES2D
 
 #include "opencv2/core/core.hpp"
 #include "opencv2/features2d/features2d.hpp"
 #include "opencv2/highgui/highgui.hpp"
 #include "opencv2/cudafeatures2d.hpp"
-#include "opencv2/nonfree/cuda.hpp"
+#include "opencv2/xfeatures2d/cuda.hpp"
 
 using namespace std;
 using namespace cv;