Fix build against setuptools 65

[sthibaul]

The newer setuptools warns:

/usr/lib/python3/dist-packages/_distutils_hack/init.py:18: UserWarning: Distutils was imported before Setuptools, but importing Setuptools also replaces the distutils module in sys.modules. This may lead to undesirable behaviors or errors. To avoid these issues, avoid using distutils directly, ensure that setuptools is installed in the traditional way (e.g. not an editable install), and/or make sure that setuptools is always imported before distutils.

So we have to import setuptools before any distutils import.