ENH: Add option Slicer_ITKV3_COMPATIBILITY. See #3825

This option enabled by default will allow (if disabled) to build Slicer
with ITKv3 compatibility later disabled and ITK_USE_64BITS_IDS enabled.

Co-authored-by: Bradley Lowekamp <blowekamp@mail.nih.gov>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23730 3bd1e089-480b-0410-8dfb-8563597acbee