_PyOS_SigintEvent() is needed for interruptible waiting on main thread

Bug report

Bug description:

Moved from https://github.com/python/cpython/pull/108605#issuecomment-2521215855

In https://github.com/python/cpython/pull/108605, _PyOS_SigintEvent was removed from the public headers.

TensorStore relies on that function here: https://github.com/google/tensorstore/blob/eda046b10158e7d82fdb0f23aeecdfdeb8ac5aa3/python/tensorstore/future.cc#L105 to enable synchronously blocking on the readiness of a custom Future type while allowing Ctrl+C to interrupt when running on the main thread.

The current workaround is to manually declare the function since the symbol is still available.

I'm not aware of a usable alternative. Since signal.set_wakeup_fd only allows a single fd to be set globally, it isn't usable from a library. The best alternative would probably be to poll by waking up every few hundred milliseconds.

CPython versions tested on:

3.13

Operating systems tested on:

No response

首先检查 CPython PR #108605，以及 TensorStore 的 python/tensorstore/future.cc 第 105 行中对 _PyOS_SigintEvent 的使用。跟踪移除公共头文件声明会如何影响扩展库，并比较可用的信号唤醒替代方案。完成的标准是为库提供一种受支持的方式，使其能够中断主线程上的同步等待，同时保留 Ctrl+C 的行为。