bug#9712: 24.0.50; doc about byte-compiling `defcustom'

[Drew Adams]

> > The bug has been there for multiple major Emacs releases now -
> > a decade or so, and appears to have been introduced intentionally.
> > If there is no plan to fix it soon, perhaps the info that is in the
> > comments should at least be conveyed to users.
> 
> The introduction of lexical-binding makes this issue more serious
> because this code does not obey the lexical-binding variable (and
> escapes the sanity checks of cconv.el, hence occasionally hiding
> problems when converting to lexical-binding).

So will this be fixed in Emacs 24.1 then?  +1