This allows building against the Python libraries even when the
Python interpreter/executable is missing. The correct extensions
for the binary modules will be guessed, the tests will fail,
and the bytecode for any pure-Python modules will not be
precompiled.
This also allows us to generate a suitable __init__.py for fixing
up PATH and/or __path__ on platforms that need it to properly
import Python extension modules.
This also involves the creation a new include: Python.cmake
This file will contain utility functions for building Python
modules and installing Python packages.
