bug#51132: Make sure user is doubly aware of finished complilations

[積丹尼 Dan Jacobson]

(info "(emacs) Compilation"):

"While the compilation is running … the word ‘Compiling’ appears in
all mode lines."

That's good. Because "Nobody is going to sit in the Laundromat watching
the dryer spin." They'll be somewhere else doing something else. (I.e.,
they won't be staring at the *compilation* buffer.)

OK, but then it disappears when the compilation is over.

(It's like "you are about to become the proud father..." and then *poof*,
No cigar. Nothing.)

It should become "Compilation Finished" and red, and flashing, etc. you
know.

Else "who is going to remember that they had some clothes left there in
the clothes dryer?"

And when it finally comes time for save-buffers-kill-emacs, there should
be a question: "You have a Compilation buffer that you haven't even
looked at once. Surely you forgot that you had an important compilation
job. Would you like to have one last look at its results before exiting
emacs? You know it has 34 lines of genuine output that you surely forgot
about during snack time.

Don't get upset. Emacs cares about you. If you think emacs is too pushy,
then do as you would with a cronjob, Make sure your STDOUT and STDERR
don't end up in the *compilation* buffer, and make sure to exit 0 and
not 1, etc. And we here at emacs won't bother you about it next time."

emacs-version "27.1"