There's a closed pull request on the void-packages repository

musl: add support for SIGEV_THREAD_ID timers
https://github.com/void-linux/void-packages/pull/39279

Description:
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#### Testing the changes
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[ci skip]

This avoids having to use the `sigev_notify_function` variable to set the value `sigev_notify_thread_id` and defines `SIGEV_THREAD_ID`.
This is useful for the gcc12 PR: https://github.com/void-linux/void-packages/pull/34902 (specifically libgo)

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