bug#20445: excessive redisplay / echo area resizing during byte-compilation

[Stefan Monnier <monnier@iro.umontreal.ca>]

>     (apply #'message format args)
>     (unless byte-compile--interactive
>       (message nil)))

This is the problem: in order to "not emit a message" this code emits
the message and then immediately hides it by emitting "the empty
message" on top of it.

Since `message' redisplays right away (rather than waiting for the next
"idle" moment to perform redisplay, as is the case for normal buffer
changes), this result in a lot of wasted work, and it won't truly do
what was intended:
- If your machine/display is slow enough, you will see it
- If your system "prints" messages by speaking them out loud (e.g. with
  emacspeak) you will hear them.

Why not just do:

     (when byte-compile--interactive
       (apply #'message format args))

?

        Stefan