Libkface now depand of last stable OpenCV library version 2.4.9

This prevent internal crash int Cv:Algorithm that we cannot handle in libkface as exception.
Now, Face Recognition do not crash but still report Exception at training operations, especially about wrong Cv:Matrix size :

digikam(8673)/digikam (core) Digikam::DImg::load:"/mnt/data2/photos/GILLES/NEW/Adrien/2010-04-13/20100413_009.jpg"  :
JPEG file identified
OpenCV Error: Assertion failed (0 <= _dims && _dims <= CV_MAX_DIM) in setSize, file /mnt/devel/opencv/modules/core/src/matrix.cpp, line 89
digikam(8673)/KFACE: cv::Exception training LBPH: /mnt/devel/opencv/modules/core/src/matrix.cpp:89: error: (-215) 0 <=_dims && _dims <= CV_MAX_DIM in function setSize

It still a problem somwhere, but it's better than previous state.

CCBUGS: 335624
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CCBUGS: 326586
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CCBUGS: 324774
CCBUGS: 323888
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CCBUGS: 309027
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CCBUGS: 285517