COMP: Fix WrapITK.pth path on windows

This error only happens with the option Slicer_USE_ITKPython enabled.

The WrapITK path isn't taking in consideration the multi-configuration
style for windows. Adding the CMAKE_CFG_INTDIR variable fixes this.

Since on other single configuration generators (like make) the variable
reduces to ".", we can simply interject it where needed.

Reviewed-by: Jean-Christophe Fillion-Robin <jchris.fillionr@kitware.com>

From: Johan Andruejol <johan.andruejol@kitware.com>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@24679 3bd1e089-480b-0410-8dfb-8563597acbee