Bug report

Bug description:

Currently, the POSIX sysconfig data is generated with the Makefile from the host interpreter, instead of the target. This results in incorrect data, as demonstrated by https://github.com/python/cpython/actions/runs/12090193539/job/33716932397?pr=127426.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• GH-127429: fix sysconfig data generation on cross-builds #127430