add cv::gpu::StreamAccessor::wrapStream method

it allows to import existed CUDA stream to OpenCV

modules/gpu/include/opencv2/gpu/stream_accessor.hpp

@@ -57,6 +57,7 @@ namespace cv
         struct StreamAccessor
         {
             CV_EXPORTS static cudaStream_t getStream(const Stream& stream);
+            CV_EXPORTS static Stream wrapStream(cudaStream_t stream);
         };
     }
 }