bug#14926: 24.3.50; Warning "`make-variable-buffer-local' should be called at toplevel"

[Drew Adams]

> > FWIW, looking at the change I've had the same reaction as Drew.
> 
> Well, it was the best short formulation that came to my mind.
...
> The "shortish" part is the problem.

Is this short enough and clear enough?

 "Consider using `make-local-variable' instead"

The context (line #) should make it clear what the "instead" refers to.

This way we're just drawing the user's attention to the possibility
that it might be more appropriate to use `make-local-variable' in that
context.  It's up to the user to check what that means, by checking the
doc.

If we could include a reference to the manual that would be even better.
The node is (elisp) `Creating Buffer-Local'.  If a link is not possible
then perhaps just add text.  Is this too long (dunno)?

 "Consider using `make-local-variable' instead [(elisp) Creating Buffer-Local]

(Yes, links or textual references from product to doc can mean more
maintenance, unless they can be updated automatically.  But they can
help users.)