COMP: Update excluding segmentation-related methods for wrapping

VTK deprecated the BTX/ETX markers, and therefore wrapping code in the markers
no longer excludes the code from being wrapped. Since wrapping fails on these
lines, exclude them using the preprocessor macro defined during wrapping.

This resolves errors such as the following:

vtkWrapPython-7.1: In /path/to/Slicer-build/Libs/vtkSegmentationCore/vtkSegmentation.h:122: syntax is ambiguous.

See https://github.com/Kitware/VTK/commit/55878a2.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@25224 3bd1e089-480b-0410-8dfb-8563597acbee