OCL: Optimize OpenCL version of StereoBM function

1. Fix problems on NVidia devices.
2. Move some arguments to build options
3. Refactoring some code.

http://ocl.itseez.com/intel/export/perf/pr/3284/report/

check_regression=*OCL*StereoBM*
test_filter=*OCL*StereoBM*
test_modules=calib3d
build_examples=OFF
All this algorithm is big bottleneck :)
We need many calculation, and if we try to vectorize them, we can't because `WSZ` and `NUM_DISP` are arbitraty and don't divisible on 4 or 8.
I think @KonstantinMatskevich created very good algorithm of walk around the square, i checked another ways to do this and had big performance degradation.