OSError 9 when using KqueueSelector and multiprocessing

[Emru1]

Bug report

Bug description:

KqueueSelector fails when created in parent process and used in child process with an OSError 9.
Tested on FreeBSD 13 and Python 3.9
I am not sure if this is relatable to #110395

import selectors
import multiprocessing

class Test(multiprocessing.Process):
    def __init__(self):
        super().__init__()
        self.s = selectors.KqueueSelector()

    def run(self):
        self.s.select()

if __name__ == '__main__':
    t = Test()
    t.start()

Process Test-1:
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/multiprocessing/process.py", line 315, in _bootstrap
    self.run()
  File "/n/home/emru/test.py", line 10, in run
    self.s.select()
  File "/usr/local/lib/python3.9/selectors.py", line 562, in select
    kev_list = self._selector.control(None, max_ev, timeout)
OSError: [Errno 9] Bad file descriptor

CPython versions tested on:

3.9

Operating systems tested on:

Other

### Tasks

[ronaldoussoren]

This is a duplicate of #110395, which mentions the root cause for the error.

[ronaldoussoren]

To expand on my previous message (and phrase it correctly):

This is related of #110395, but slightly different. The system kqueue API does not support creating the kqueue in a parent proces and use it in a child. That's not something we can work around.

That means that your code will give an error even if the #110395 is fixed (the PR on that issue will close all kqueue objects in the child proces).