[3.12] gh-77377: Ensure multiprocessing SemLock is valid for spawn-based Process...

[3.12] gh-77377: Ensure multiprocessing SemLock is valid for spawn-based Process before serializing it (GH-107275) (#108377)

gh-77377: Ensure multiprocessing SemLock is valid for spawn-based Process before serializing it (GH-107275)

Ensure multiprocessing SemLock is valid for spawn Process before serializing it.

Creating a multiprocessing SemLock with a fork context, and then trying to pass it to a spawn-created Process, would segfault if not detected early.

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(cherry picked from commit 1700d34d314f5304a7a75363bda295a8c15c371f)

Co-authored-by: albanD <desmaison.alban@gmail.com>
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Antoine Pitrou <pitrou@free.fr>