modules: python: better handling of the Python paths for Debian
modules: python: better handling of the Python paths for Debian

Hardcoding the name is fragile, and enabling it based on the existence of
/etc/debian_version (as the is_debianlike helper does) will result in
incorrect paths if the Python binary is not provided by Debian.

Using the deb_system distuils scheme instead makes sure we use the
install path from the current interpreter, which Debian could change
between releases, and gives us the correct value on Python installations
that are not provided by Debian (eg. deadsnakes, Github Action Python,
etc.)

Do notice, though, that there is still no guarantee that these are the
correct paths, as they assume all schemes paths have the install prefix
as a base, see #9284.

Signed-off-by: Filipe Laíns <d780ea131edc6126ff48fa0382b66c02d54b57a5@riseup.net>

pexip/meson,mesonbuild/meson,pexip/meson,pexip/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,pexip/meson,pexip/meson,pexip/meson,pexip/meson,pexip/meson,pexip/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson