closefrom check is too strict

[thesamesam]

Bug report

Bug description:

closefrom(3) is available with >=glibc-2.34 on Linux (and Hurd, but, well...)

The check in Python/fileutils.c is a bit too strict, as it hardcodes FreeBSD. This excludes both the aforementioned systems but also other BSDs where I believe it's available.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-112970: Detect and use closefrom() on platforms where it is available #112969

[thesamesam]

We noticed this when poking at a swarm of close calls on an older kernel.

[erlend-aasland]

Resolved with:

• gh-112970: Detect and use closefrom() on platforms where it is available #112969