python3: fix python initialization
vtkPythonInterpreter::SetupPythonPrefix
calls Py_SetProgramName
to guide the initialization of Python. However, it called a few
Py_Get..
functions which caused Python3 config to get partially
initialized using values prior to calling the Py_SetProgramName
. This
was resutling in packages failing to init Python correctly with an
embedded Python package. Fixed that.
backport: paraview/release
Edited by Utkarsh Ayachit