SSE2 optimization of cv::integral

```
integral::Size_MatType_OutMatDepth::(127x61, 8UC1, CV_32S)    0.009 ms  0.004 ms     2.08
integral::Size_MatType_OutMatDepth::(640x480, 8UC1, CV_32S)   0.320 ms  0.170 ms     1.88
integral::Size_MatType_OutMatDepth::(1280x720, 8UC1, CV_32S)  0.977 ms  0.442 ms     2.21
integral::Size_MatType_OutMatDepth::(1920x1080, 8UC1, CV_32S) 2.175 ms  1.148 ms     1.90
```