Subject: bug#55628: debug-timer-check fails on macOS 11.6.6

From: Eli Zaretskii <[email-masked]>
Date: Wed, 25 May 2022 17:02:03 +0300

> Cc: [email-masked]
> From: Mattias Engdegård <[email-masked]>
> Date: Wed, 25 May 2022 15:05:32 +0200
> 
> Thanks for checking. Apparently pending_signals is never set; handle_alarm_signal is never called.
> More digging shows that set_alarm always sets the interval timer to at least 1 ms in the future even if the timer has expired.
> 
> The attached patch makes set_alarm signal SIGALRM immediately if the timer is due. We could call the signal handler directly but this way it should work correctly if the signal is masked at the moment. What do you think?

I'd prefer not to change the logic of set_alarm just to have a
debugging aid working.  Can we come up with a more compatible change,
which doesn't affect calls to set_alarm except during this test?

Thanks.