* Use sysconfig in Python >= 3.10
Rely on sysconfig for installation paths for Python >= 3.10. distutils
has been deprecated and will be removed.
Fixes: #3677
* Explicitly select the posix_prefix scheme for platinclude on Debian
Debian's default scheme is posix_local, for installing locally-built
packages to /usr/local/. We want to find the Python headers in /usr/,
so search posix_prefix.
