message: GAPI - KW fixes
  - avoid overflow in own::Mat::total() and according tests, part 2
diff: @@ -42,7 +42,7 @@ TEST(OwnMat, Create)
  ASSERT_NE(m.data, nullptr);
  ASSERT_EQ((cv::gapi::own::Size{m.cols, m.rows}), size);
  - ASSERT_EQ(m.total(), static_cast<size_t>(size.height*size.width));
  + ASSERT_EQ(m.total(), static_cast<size_t>(size.height) * size.width);
  ASSERT_EQ(m.type(), CV_8UC1);
  ASSERT_EQ(m.depth(), CV_8U);
  ASSERT_EQ(m.channels(), 1);
  @@ -61,7 +61,7 @@ TEST(OwnMat, CreateND)
  ASSERT_NE(nullptr , m.data );
  ASSERT_EQ((cv::gapi::own::Size{0,0}), (cv::gapi::own::Size{m.cols, m.rows}));
  - ASSERT_EQ(static_cast<size_t>(dims[0]*dims[1]*dims[2]*dims[3]), m.total());
  + ASSERT_EQ(multiply_dims(dims), m.total());
  ASSERT_EQ(CV_32F , m.type() );
  ASSERT_EQ(CV_32F , m.depth() );
  ASSERT_EQ(-1 , m.channels());
  @@ -307,7 +307,7 @@ TEST(OwnMat, AssignNDtoRegular)
  ASSERT_NE(nullptr , a.data);
  ASSERT_EQ(sz , (cv::gapi::own::Size{a.cols, a.rows}));
  - ASSERT_EQ(static_cast<size_t>(sz.width*sz.height), a.total());
  + ASSERT_EQ(static_cast<size_t>(sz.width) * sz.height, a.total());
  ASSERT_EQ(CV_8U , a.type());
  ASSERT_EQ(CV_8U , a.depth());
  ASSERT_EQ(1 , a.channels());
  @@ -322,7 +322,7 @@ TEST(OwnMat, AssignNDtoRegular)
  ASSERT_NE(nullptr , a.data);
  ASSERT_NE(old_ptr , a.data);
  ASSERT_EQ((cv::gapi::own::Size{0,0}), (cv::gapi::own::Size{a.cols, a.rows}));
  - ASSERT_EQ(static_cast<size_t>(dims[0]*dims[1]*dims[2]*dims[3]), a.total());
  + ASSERT_EQ(multiply_dims(dims), a.total());
  ASSERT_EQ(CV_32F , a.type());
  ASSERT_EQ(CV_32F , a.depth());
  ASSERT_EQ(-1 , a.channels());
  @@ -342,7 +342,7 @@ TEST(OwnMat, AssignRegularToND)
  ASSERT_NE(nullptr , a.data);
  ASSERT_EQ((cv::gapi::own::Size{0,0}), (cv::gapi::own::Size{a.cols, a.rows}));
  - ASSERT_EQ(static_cast<size_t>(dims[0]*dims[1]*dims[2]*dims[3]), a.total());
  + ASSERT_EQ(multiply_dims(dims), a.total());
  ASSERT_EQ(CV_32F , a.type());
  ASSERT_EQ(CV_32F , a.depth());
  ASSERT_EQ(-1 , a.channels());
  @@ -357,7 +357,7 @@ TEST(OwnMat, AssignRegularToND)
  ASSERT_NE(nullptr , a.data);
  ASSERT_NE(old_ptr , a.data);
  ASSERT_EQ(sz , (cv::gapi::own::Size{a.cols, a.rows}));
  - ASSERT_EQ(static_cast<size_t>(sz.width*sz.height), a.total());
  + ASSERT_EQ(static_cast<size_t>(sz.width) * sz.height, a.total());
  ASSERT_EQ(CV_8U , a.type());
  ASSERT_EQ(CV_8U , a.depth());
  ASSERT_EQ(1 , a.channels());
  