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

[Drew Adams]

Please make it possible to call this function without it displaying a
message.  E.g., add an optional MSG argument that is always non-nil
interactively.
 
One motivation:
 
An Emacs function might do a series of things, including calling
`save-buffer'.  Sometimes the whole series could take a while, and a
caller of the function might want to give a specific progress message:
"Foo-barring..." and end with "Foo-barring...done".  When the series of
operations includes `save-buffer' this messaging is interrupted, and the
user sees a message from `save-buffer', with no `...' to indicate that
the overall operation (series) is not finished.
 
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.
 
Same thing applies for `basic-save-buffer'.  These functions are called
from Lisp.  They deserve optional MSG args to control message display.
(Obviously, this applies only to the use of `message', not also to
reading input or raising errors.)

In GNU Emacs 24.0.92.1 (i386-mingw-nt5.1.2600) of 2011-12-06 on MARVIN
 Windowing system distributor `Microsoft Corp.', version 5.1.2600
 configured using `configure --with-gcc (4.6) --no-opt --cflags
 -ID:/devel/emacs/libs/libXpm-3.5.8/include
 -ID:/devel/emacs/libs/libXpm-3.5.8/src
 -ID:/devel/emacs/libs/libpng-dev_1.4.3-1/include
 -ID:/devel/emacs/libs/zlib-dev_1.2.5-2/include
 -ID:/devel/emacs/libs/giflib-4.1.4-1/include
 -ID:/devel/emacs/libs/jpeg-6b-4/include
 -ID:/devel/emacs/libs/tiff-3.8.2-1/include
 -ID:/devel/emacs/libs/gnutls-2.10.1/include --ldflags
 -LD:/devel/emacs/libs/gnutls-2.10.1/lib'