message: Fix StereoBM ROI selection
  Fix StereoBM ROI (Region of interest) selection for stereo
  images used by block matching algorithm
diff: @@ -1184,8 +1184,8 @@ public:
  parallel_for_(Range(0, 2), PrefilterInvoker(left0, right0, left, right, _buf, _buf + bufSize1, &params), 1);
  Rect validDisparityRect(0, 0, width, height), R1 = params.roi1, R2 = params.roi2;
  - validDisparityRect = getValidDisparityROI(R1.area() > 0 ? Rect(0, 0, width, height) : validDisparityRect,
  - R2.area() > 0 ? Rect(0, 0, width, height) : validDisparityRect,
  + validDisparityRect = getValidDisparityROI(R1.area() > 0 ? R1 : validDisparityRect,
  + R2.area() > 0 ? R2 : validDisparityRect,
  params.minDisparity, params.numDisparities,
  params.SADWindowSize);
  