bug#51820: 29.0.50; process_pending_signals is almost useless without SIGIO

[Ken Brown <kbrown@cornell.edu>]

On 11/14/2021 1:48 AM, Eli Zaretskii wrote:
>> Date: Sat, 13 Nov 2021 18:25:55 -0500
>> Cc: 51820@debbugs.gnu.org, Eli Zaretskii <eliz@gnu.org>
>> From: Ken Brown <kbrown@cornell.edu>
>>
>>> In that case, perhaps someone using Cygwin (i.e., not me) could look into this.
>>> Evidently it has not been much of a practical problem all these years.
>>
>> It's hard to know whether it's been a problem.  Maybe emacs would be more
>> responsive to C-g on Cygwin if we removed the #ifdef from handle_async_input.
>> My preference would be to try that (on master of course) and see if anything breaks.
>>
>> Eli, WDYT?
> 
> Sure, feel free to install such a change on master.

Done.

> I don't know how
> many Cygwin users track the Emacs master branch, but if there are more
> than a couple, perhaps even provide a variable exposed to Lisp that
> users could tweak to see the result without rebuilding and without
> leaving the session.

Good idea.  I think I'll wait a couple weeks so that I can see how the change 
works myself, as well as to see if anyone notices.  But then I might do that. 
For now I'm closing the bug.

Ken