fixed warnings under windows

modules/gpu/test/test_hough.cpp

@@ -89,7 +89,7 @@ TEST_P(HoughLines, Accuracy)
         const bool useRoi = GET_PARAM(2);
 
         const float rho = 1.0f;
-        const float theta = 1.5f * CV_PI / 180.0f;
+        const float theta = (float) (1.5 * CV_PI / 180.0);
         const int threshold = 100;
 
         cv::Mat src(size, CV_8UC1);

modules/gpu/test/test_labeling.cpp

@@ -82,7 +82,7 @@ namespace {
             int cc = -1;
 
             int* dist_labels = (int*)labels.data;
-            int pitch = labels.step1();
+            int pitch = (int) labels.step1();
 
             unsigned char* source = (unsigned char*)image.data;
             int width = image.cols;

modules/gpu/test/test_video.cpp

@@ -606,8 +606,8 @@ static void FastOpticalFlowBM_gold(const cv::Mat_<uchar>& I0, const cv::Mat_<uch
                 }
             }
 
-            velx(y, x) = bestDx;
-            vely(y, x) = bestDy;
+            velx(y, x) = (float) bestDx;
+            vely(y, x) = (float) bestDy;
         }
     }
 }