[clustering] K-means #1476
[clustering] K-means #1476

- Fix for Visual Studio (error C3016: 'X': index variable in OpenMP
'for' statement must have signed integral type)

openMVG/openMVG,openMVG/openMVG,openMVG/openMVG,openMVG/openMVG,openMVG/openMVG