bug#10345: 24.0.92; `save-buffer' and `basic-save-buffer': add MSG arg

[Drew Adams]

> If you wish to save buffers without messaging, you use `write-region' or
> the like.  `save-buffers' is a very user level function.  Closing.

No. `write-region' does not do the same thing at all.
And no, `save-buffers' is not only "a very user level function".

As I said:

 > In sum, since this function is sometimes called from Lisp,
 > it makes little sense for it to systematically display a
 > message.  A caller should be able to control the messaging
 > behavior.

Do you deny that this function is sometimes called from Lisp?
If you instead accept that, then why shouldn't a caller of it
be able to control the messaging behavior?

What does it cost Emacs to add an optional MSG argument?