don't use constructors for C API structures

modules/imgproc/src/floodfill.cpp

@@ -641,15 +641,8 @@ cvFloodFill( CvArr* arr, CvPoint seed_point,
              CvScalar newVal, CvScalar lo_diff, CvScalar up_diff,
              CvConnectedComp* comp, int flags, CvArr* maskarr )
 {
-#if defined __GNUC__ && __GNUC__ >= 8
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wclass-memaccess"
-#endif
     if( comp )
         memset( comp, 0, sizeof(*comp) );
-#if defined __GNUC__ && __GNUC__ >= 8
-#pragma GCC diagnostic pop
-#endif
 
     cv::Mat img = cv::cvarrToMat(arr), mask = cv::cvarrToMat(maskarr);
     int area = cv::floodFill(img, mask, seed_point, newVal,