Use cvRound to suppress Windows warnings

modules/xphoto/src/grayworld_white_balance.cpp

@@ -67,7 +67,7 @@ namespace cv { namespace xphoto {
         // Calculate sum of pixel values of each channel
         const uchar* src_data = src.ptr<uchar>(0);
         unsigned long sum1 = 0, sum2 = 0, sum3 = 0;
-        unsigned int thresh255 = round(thresh * 255);
+        unsigned int thresh255 = cvRound(thresh * 255);
         int i = 0;
 #if CV_SIMD128
         v_uint8x16 v_inB, v_inG, v_inR;

modules/xphoto/test/test_grayworld.cpp

@@ -20,7 +20,7 @@ namespace cvtest {
         const uchar* src_data = src.ptr<uchar>(0);
         unsigned long sum1 = 0, sum2 = 0, sum3 = 0;
         int i = 0;
-        unsigned int minRGB, maxRGB, thresh255 = round(thresh * 255);
+        unsigned int minRGB, maxRGB, thresh255 = cvRound(thresh * 255);
         for ( ; i < N3; i += 3 )
         {
             minRGB = std::min(src_data[i], std::min(src_data[i + 1], src_data[i + 2]));