1) more convenient naming for samples gpu

2) added mask support to device 'transform' function 
3) sample hog gpu: waitKey(1) -> waitKey(3), in other case image is not displayed.

samples/gpu/CMakeLists.txt

@@ -24,11 +24,11 @@ if (BUILD_EXAMPLES)
     #      Define executable targets
     # ---------------------------------------------
     MACRO(MY_DEFINE_EXAMPLE name srcs)
-        set(the_target "example_${name}")
+        set(the_target "example_gpu_${name}")
     	add_executable(${the_target} ${srcs})
 		set_target_properties(${the_target} PROPERTIES
 		    OUTPUT_NAME "${name}"
-		    PROJECT_LABEL "(EXAMPLE) ${name}")
+		    PROJECT_LABEL "(EXAMPLE_GPU) ${name}")
     	add_dependencies(${the_target} opencv_core opencv_flann opencv_imgproc opencv_highgui
     	    opencv_ml opencv_video opencv_objdetect opencv_features2d
     	    opencv_calib3d opencv_legacy opencv_contrib opencv_gpu)

samples/gpu/hog.cpp

@@ -283,7 +283,7 @@ void App::RunOpencvGui()
             // Show results
             putText(img_to_show, GetPerformanceSummary(), Point(5, 25), FONT_HERSHEY_SIMPLEX, 1.0, Scalar(0, 0, 255), 2);
             imshow("opencv_gpu_hog", img_to_show);
-            HandleKey((char)waitKey(1));
+            HandleKey((char)waitKey(3));
 
             if (settings.src_is_video)
             {