calib3d: use `Mat::reserveBuffer()` instead of `.create()`

to allocate memory >2Gb

modules/calib3d/src/stereosgbm.cpp

@@ -1492,7 +1492,9 @@ static void computeDisparitySGBM_HH4( const Mat& img1, const Mat& img2,
 
     if( buffer.empty() || !buffer.isContinuous() ||
         buffer.cols*buffer.rows*buffer.elemSize() < totalBufSize )
-        buffer.create(1, (int)totalBufSize, CV_8U);
+    {
+        buffer.reserveBuffer(totalBufSize);
+    }
 
     // summary cost over different (nDirs) directions
     CostType* Cbuf = (CostType*)alignPtr(buffer.ptr(), ALIGN);