we don't need opencv3::face contrib module. This one is now integrated in FaceEngines as well.

As usual, OpenCV make the puzzle. With version 3, and all the contrib modules never released as a dedicated tarball,
this code will stay in beta stage for a while. This is not a safe situation, if OpenCV3 packager do not integrate face module in standard.
The OpenCV3::face implementation is just adated to be compiled outside the contrib structure, that all...
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