a lot of refactoring

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

@@ -413,7 +413,7 @@ namespace cv
             void operator()(const GpuMat& left, const GpuMat& right, GpuMat& disparity);
 
             //! Acync version
-            void operator()(const GpuMat& left, const GpuMat& right, GpuMat& disparity, const Stream& stream);
+            void operator()(const GpuMat& left, const GpuMat& right, GpuMat& disparity, Stream& stream);
 
             int ndisp;
 
@@ -462,7 +462,7 @@ namespace cv
             void operator()(const GpuMat& left, const GpuMat& right, GpuMat& disparity);
 
             //! Acync version
-            void operator()(const GpuMat& left, const GpuMat& right, GpuMat& disparity, const Stream& stream);
+            void operator()(const GpuMat& left, const GpuMat& right, GpuMat& disparity, Stream& stream);
 
             int ndisp;
 

modules/gpu/src/beliefpropagation_gpu.cpp

@@ -212,7 +212,7 @@ void cv::gpu::StereoBeliefPropagation::operator()(const GpuMat& left, const GpuM
     ::stereo_bp_gpu_operator(ndisp, iters, levels, max_data_term, data_weight, max_disc_term, disc_single_jump, msg_type, u, d, l, r, u2, d2, l2, r2, datas, out, left, right, disp, 0);
 }
 
-void cv::gpu::StereoBeliefPropagation::operator()(const GpuMat& left, const GpuMat& right, GpuMat& disp, const Stream& stream)
+void cv::gpu::StereoBeliefPropagation::operator()(const GpuMat& left, const GpuMat& right, GpuMat& disp, Stream& stream)
 {
     ::stereo_bp_gpu_operator(ndisp, iters, levels, max_data_term, data_weight, max_disc_term, disc_single_jump, msg_type, u, d, l, r, u2, d2, l2, r2, datas, out, left, right, disp, StreamAccessor::getStream(stream));
 }