Support building as a proper [C]Python extension, and/or by distutils

On request, uWSGI will create a setuptools entrypoint to implement
bin/uwsgi, and will behave more like an extension. Exports uwsgi.ORIG_ARGV and uwsgi.NEW_ARGV... ex:

    # python -i -c \
        'import uwsgi as u; u.setup().worker_id()==1 or u.run()' \
        --master --workers=1 --enable-threads --honour-stdin \
        --auto-procname --http :8000

Relies on new_argc/new_argv support in 2.1