[fuseCut] fuse: make angle stats computation optional
[fuseCut] fuse: make angle stats computation optional

debug code that does not participate in 'angleScore' computation
* now depends on 'FUSE_COMPUTE_ANGLE_STATS' definition 
* disabled by default
* disabled if OpenMP does not provide min/max reduction clauses (< 3.1)
poparteu/openMVG,poparteu/openMVG,poparteu/openMVG,poparteu/openMVG