gh-133644: Remove PySys_SetArgv* for 3.15

[xuantengh]

Remove PySys_SetArgv and PySys_SetArgvEx.

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📚 Documentation preview 📚: https://cpython-previews--136277.org.readthedocs.build/

• Issue: Remove deprecated C API objects slated for removal in 3.15 #133644

[ZeroIntensity]

We shouldn't remove the entry here, we should just mark them as abi_only = true.

[zooba]

Which will preserve them in python3dll.c, which is the actual breaking change (or at least the one that can be easily seen in a source diff).

Arguably they should stay in the header files as well, possibly only when Py_LIMITED_API is set. The functionality can change if it needs to, though ideally wouldn't break every existing user.

[picnixz]

Please check if there are projects in the wild that use this. See for instance the case of PyWeakRef_GetObject where we delayed the removal for now until less projects are using it. And also, we should coordinate with the compat project. Finally, add a section for this removal in What's New as well as possible fallbacks.

[xuantengh]

Please check if there are projects in the wild that use this.

I have some rough and preliminary search in GitHub and find some projects like:

• https://github.com/plotdevice/plotdevice
• https://github.com/crftwr/keyhac-win
• https://github.com/renpy/renpyweb

still use these C functions.

I can have a more detail exploration for popular PyPI packages later.

[xuantengh]

@picnixz I search the top 300 popular PyPI packages and find PySys_SetArgv appears in the following 2:

• cython
• orjson

[picnixz]

Well cython is a major project that we don't want to break. orjson is, iirc, simd-accelerated JSON so we don't want to break it either. They should first upgrade their code and then we'll remove the functions on our side I think.