BUG #14263. Fix Python path issue with Windows installers.

We need to add the location of *Python.so files to sys.path since they are no
longer in the same place as the ParaView shared libraries.

Change-Id: I21342df664c7a2e7948c8cb015ee5a100848a582
Merge topic '14263_fix_python_in_installs' into next

f27b51c BUG #14263. Fix Python path issue with Windows installers.