fixes for gpu module:

- fixed printCudaDeviceInfo for new CC
- fixed some compilation errors and warnings
- removed unset command from CMake script
- removed unused std imports

modules/core/include/opencv2/core/cuda_devptrs.hpp

@@ -177,6 +177,20 @@ namespace cv
 //#undef __CV_GPU_DEPR_BEFORE__
 //#undef __CV_GPU_DEPR_AFTER__
 
+        namespace device
+        {
+            using cv::gpu::PtrSz;
+            using cv::gpu::PtrStep;
+            using cv::gpu::PtrStepSz;
+
+            using cv::gpu::PtrStepSzb;
+            using cv::gpu::PtrStepSzf;
+            using cv::gpu::PtrStepSzi;
+
+            using cv::gpu::PtrStepb;
+            using cv::gpu::PtrStepf;
+            using cv::gpu::PtrStepi;
+        }
     }
 }