Virtualenv: Support Pythons without distutils

[gaborbernat]

At the moment interpreter lookup fails when distutils is not available, e.g. on some Ubuntu Python distributions. Error:

113 failed to query /usr/bin/python3.6 with code 1 err: 'Traceback (most recent call last):\n  File "/home/manos/.local/lib/python3.8/site-packages/virtualenv/discovery/py_info.py", line 16, in <module>\n    from distutils.command.install import SCHEME_KEYS\nModuleNotFoundError: No module named \'distutils.command\'\n' [INFO cached_py_info:38]

See https://github.com/pypa/virtualenv/issues/1643#issuecomment-665691388.

[hynek]

To help desperate Googlers (me, yesterday): if you get RuntimeError: failed to find interpreter for Builtin discover of python_spec='3.9' on Ubuntu or debian and you positively know that the interpreter is installed, it might be that you're missing python3.9-distutils.