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

Without this, sysconfig would report the target location, which is not
what we want in cross-builds. This is used in particular by
latest autoconf-archive m4 macros, which have migrated from
(removed in py 3.12) distutils to setuptools.

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