python3: backport and fix target musl libc detection

python3: backport and fix target musl libc detection

Patch 030:
Backported from Python main branch[^1] for Python to distinguish between glibc and musl libc SOABI.

Patch 131:
Changes PLATFORM_TRIPLET -gnu/-musl suffix detection (performed by the backported patch)
to be based on the target OS instead of the building OS.

See included patches for more detailed descriptions.

Specifically this fixes cross-compilation for mpc8548 CPUs with SPE instructions[^2] enabled.

[^1]: merged to python:main as https://github.com/python/cpython/pull/24502 'bpo-43112: detect musl as a separate SOABI'
[^2]: https://www.nxp.com/docs/en/reference-manual/SPEPEM.pdf

Co-authored-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Šimon Bořek <simon.borek@nic.cz>