RE: bytecomp.el: issue warning when `mapcar' is called for effect

["Drew Adams" <drew.adams@oracle.com>]

> This makes the byte-compiler mention `mapc' and `dolist' where one of
> them is preferable over `mapcar'.
>
> +      "`mapcar' called for effect; use `mapc' or `dolist' instead"))

How about "consider using" instead of "use"? This is, after all, a warning,
not an error.

Some libraries aim for use with multiple Emacs versions, and some Emacs
versions don't have `mapc' or `dolist' (and a library might not have
required `cl' at compile time). When users see such warnings, they can freak
out, submit bug reports to the library maintainers, etc.

If the message length is a problem, drop "instead" -

 "`mapcar' called for effect; consider using `mapc' or `dolist'"
is not much longer than
 "`mapcar' called for effect; use `mapc' or `dolist' instead"