Revert "python3-native: further tweak to sysconfig.py to find python includes correctly"

Unfortunately, sysconfig is used by:
- setuptools to find out where to install new headers
- autoconf-archive to find where Python.h is

In the first case we want the target location, in the second case we want
the sysroot location. The second case is not yet used in the wild
(as projects such as gpgpme are using outdated distutils-based m4 macros),
but it will become a problem once python 3.12 is out, and
said projects are forced to migrate to sysconfig. Let's deal with it
then in a more careful manner, and hopefully convince upstream that
there is a general problem too.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>