[moved from opencv] Merge pull request opencv/opencv#16090 from jeffeDurand:cuda_mog2_issue_5296

* cuda_mog2_issue_5296
original commit: https://github.com/opencv/opencv/commit/5bf73457431b7d2cb87ac8c107865388dbf66642

modules/cudabgsegm/src/cuda/mog2.hpp

+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+
+#ifndef OPENCV_CUDA_MOG2_H
+#define OPENCV_CUDA_MOG2_H
+
+#include "opencv2/core/cuda.hpp"
+
+struct CUstream_st;
+typedef struct CUstream_st *cudaStream_t;
+
+namespace cv { namespace cuda {
+
+class Stream;
+
+namespace device { namespace mog2 {
+
+typedef struct
+{
+    float Tb_;
+    float TB_;
+    float Tg_;
+    float varInit_;
+    float varMin_;
+    float varMax_;
+    float tau_;
+    int nmixtures_;
+    unsigned char shadowVal_;
+} Constants;
+
+void mog2_gpu(PtrStepSzb frame, int cn, PtrStepSzb fgmask, PtrStepSzb modesUsed, PtrStepSzf weight, PtrStepSzf variance, PtrStepSzb mean, float alphaT, float prune, bool detectShadows, const Constants *const constants, cudaStream_t stream);
+void getBackgroundImage2_gpu(int cn, PtrStepSzb modesUsed, PtrStepSzf weight, PtrStepSzb mean, PtrStepSzb dst, const Constants *const constants, cudaStream_t stream);
+
+} } } }
+
+#endif /* OPENCV_CUDA_MOG2_H */