bug#6376: 23.2; byte compile add-to-list report free variable

[Kevin Ryde]

Stefan Monnier <monnier@iro.umontreal.ca> writes:
>
> Could you send it as a patch, please.

I suppose I should get my cvs head checkout sorted so as to be able to
test on the current code.  That's likely to take a while :-(

> Which part(s) so you think still need work?

I thought to make room for checking the func arg to add-hook and
friends.  But checking the variables might be enough to start with.