bug#45063: compilation-bell

[Eli Zaretskii]

> From: 積丹尼 Dan Jacobson
>  <jidanni@jidanni.org>
> Date: Sun, 06 Dec 2020 13:09:55 +0800
> 
> https://www.quora.com/Why-do-typewriters-have-a-bell
> Well compilers should too!
> Sure, at the end of a Makefile we could just put
>       beep
> but a new compilation-bell variable,
> 'always: ring after every compilation finishes
> 'long: ring only after compilations finish that took a "long time", that
>    you probably forgot are still running.

See compilation-finish-functions hook, you can put there anything you
want.

> And ring differently for failed compilations.

The functions on the above hook are called with the description of how
the compilation ended, so you can vary the result as you see fit.

Closing.