Availability of `ptsname_r` is not checked at runtime on macOS

[zanieb]

Bug report

Bug description:

Use of this was recently added in Python 3.13 but it is only available in macOS 10.13.4+ and there is not a proper runtime check for availability. This means that in python-build-standalone we need to ban the symbol instead of allowing proper weak linking.

See discussion at astral-sh/python-build-standalone#319 (comment)

Similar to #75782

CPython versions tested on:

3.13

Operating systems tested on:

macOS

Linked PRs

• gh-123797: Check for runtime availability of ptsname_r on macos #123806
• [3.13] gh-123797: Check for runtime availability of ptsname_r on macos (GH-123806) #124270

[zanieb]

This is a build issue but I can't make those.

edit: and thanks for fixing my typo