samples: gpu: removed inclusion of non-existent opencv2/contrib/contrib.hpp header, re-introduced TickMeter class in a separate header

This patch removes inclusion of opencv2/contrib/contrib.hpp header,
which does not exist anymore due to removal of opencv_contrib module.

The samples including this header appear to be doing so in order to
use TickMeter class; therefore, the latter is now provided by tick_meter.hpp
header file, located in samples/gpu folder.

samples/gpu/stereo_multi.cpp

@@ -15,9 +15,10 @@
 #include "opencv2/core.hpp"
 #include "opencv2/highgui.hpp"
 #include "opencv2/imgproc.hpp"
-#include "opencv2/contrib.hpp"
 #include "opencv2/cudastereo.hpp"
 
+#include "tick_meter.hpp"
+
 using namespace std;
 using namespace cv;
 using namespace cv::cuda;