setup: use setuptools on Windows (issue5400)
We've had a long, complicated history with setuptools. We want to
make it the universal default. But when we do, it breaks things.
`python setup.py build` is broken on Windows today. Forcing
the use of setuptools via FORCE_SETUPTOOLS=1 unbreaks things.
Since the previous bustage with making setuptools the default
was on !Windows, it seems safe to move ahead with the setuptools
transition on Windows. So this patch does that.
# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)