AIX build broken because of recent os.statx implementation.

[ayappanec]

Bug description:

The recent os.statx implementation is very specific to Linux #139178 . This broke AIX build as the configure simply checks for the presence of statx function which is available in AIX but very much different from it. https://www.ibm.com/docs/en/aix/7.3.0?topic=s-stat-fstat-lstat-statx-fstatx-statxat-fstatat-fullstat-ffullstat-stat64-fstat64-lstat64-stat64x-fstat64x-lstat64x-stat64xat-subroutine

The configure check for statx should be improved to check whether the platform is Linux or not , as well.

CPython versions tested on:

CPython main branch

Operating systems tested on:

AIX

Linked PRs

• gh-140239: Check statx availability only in Linux platforms #140249

[cmaloney]

cc: @jbosboom , @vstinner