COMP: Ensure ITKFactoryRegistration is considered when setting ITK_INCLUDE_DIRS at top-level.

This will fix build errors of the form:

.../Logic/Testing/Cxx/vtkMRMLSliceLogicTest2.cxx:49:38: error: itkFactoryRegistration.h: No such file or directory
.../Logic/Testing/Cxx/vtkMRMLSliceLogicTest2.cxx: In function 'int vtkMRMLSliceLogicTest2(int, char**)':
.../Logic/Testing/Cxx/vtkMRMLSliceLogicTest2.cxx:56: error: 'itkFactoryRegistration' is not a member of 'itk'

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21723 3bd1e089-480b-0410-8dfb-8563597acbee