GPUSmoothing → GPUImageFilterBase Relation

File in ITK/Modules/Filtering/GPUSmoothing	Includes file in ITK/Modules/Filtering/GPUImageFilterBase
include / itkGPUDiscreteGaussianImageFilter.h	include / itkGPUNeighborhoodOperatorImageFilter.h
include / itkGPUMeanImageFilter.h	include / itkGPUBoxImageFilter.h