opencv: multiple cores support

[Silex]

Hello,

OpenCV opencv_traincascade is monocore out of the box. If you compile with cmake -DWITH_TBB=1 then it builds with multiple core support, BUT it's still not enough because code in traincascade isn't parallelized.

Here is the discussion about traincascade limitations:

http://answers.opencv.org/question/63/enable-multithreading-with-tbb-during-cascade/

I read something about installing IPP to solve it, I'll give it a try.