Made samples build independent from nonfree module.

samples/cpp/matcher_simple.cpp

@@ -1,8 +1,20 @@
+#include "opencv2/opencv_modules.hpp"
 #include <stdio.h>
-#include "opencv2/core/core.hpp"
-#include "opencv2/features2d/features2d.hpp"
-#include "opencv2/highgui/highgui.hpp"
-#include "opencv2/nonfree/nonfree.hpp"
+
+#ifndef HAVE_OPENCV_NONFREE
+
+int main(int, char**)
+{
+    printf("The sample requires nonfree module that is not available in your OpenCV distribution.\n");
+    return -1;
+}
+
+#else
+
+# include "opencv2/core/core.hpp"
+# include "opencv2/features2d/features2d.hpp"
+# include "opencv2/highgui/highgui.hpp"
+# include "opencv2/nonfree/nonfree.hpp"
 
 using namespace cv;
 
@@ -56,3 +68,5 @@ int main(int argc, char** argv)
 
     return 0;
 }
+
+#endif