BUG: Remove incorrect initialization

A compiler warning indicated incorrect initialization of
minimum value.

Slicer/Modules/CLI/RobustStatisticsSegmenter/SFLSRobustStatSegmentor3DLabelMap_single.h:133:
Slicer/Modules/CLI/RobustStatisticsSegmenter/SFLSRobustStatSegmentor3DLabelMap_single.txx:874:30: warning: implicit conversion
      from 'type' (aka 'unsigned int') to 'short' changes value from 4294967295 to -1 [-Wconstant-conversion]
  m_inputImageIntensityMin = std::numeric_limits<unsigned>::max(); // yes, it's twisted so easity to compute.

The numeric_limits type needed to be made consistent with the image.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23023 3bd1e089-480b-0410-8dfb-8563597acbee