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

[Eli Zaretskii <eliz@gnu.org>]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Thu, 26 May 2022 11:57:58 +0200
> Cc: larsi@gnus.org, 55628@debbugs.gnu.org
> 
> 25 maj 2022 kl. 19.11 skrev Eli Zaretskii <eliz@gnu.org>:
> 
> > Btw, this test will never work on a platform that only has setitimer,
> > because only one ITIMER_REAL timer is guaranteed to exist, and the
> > function attempts to arm 10 timers at the same time.
> 
> That's not how the code works. `setitimer` will only be called for the first timer to expire.

Maybe I've misread the code, then.  Apologies.

> > We don't usually have testing code in a production build, so why make
> > an exception here?  Especially since atimers are an obscure feature
> > used internally by Emacs.
> 
> There's nothing bad or even unusual about including interfaces for internal testing in production builds, as long as it doesn't unduly reduce performance or cause significant bloat. It's always a trade-off, of course.

Not in principle, but we in this project don't do that.  E.g., there
are several debug-related functions and commands in xdisp.c that are
only compiled in under ENABLE_CHECKING.

So if we are going to make an exception for this case, we should have
some good reason.