COMP: Fixed some warnings on gcc using the -Wall option.

Code/BasicFilters/otbMeanShiftImageFilter.h

Code/BasicFilters/otbMeanShiftImageFilter.txx

Code/BasicFilters/otbMeanShiftImageFilterBase.h

Code/BasicFilters/otbMeanShiftImageFilterBase.txx

Code/BasicFilters/otbMeanShiftVectorImageFilter.h

Code/BasicFilters/otbMeanShiftVectorImageFilter.txx