bug#7594: 24.0.50; doc string of `line-move-visual'

[Chong Yidong]

"Drew Adams" <drew.adams@oracle.com> writes:

>  When non-nil, `line-move' moves point by visual lines.
>  This movement is based on where the cursor is displayed on the
>  screen, instead of relying on buffer contents alone.  It takes
>  into account variable-width characters and line continuation.
>
> It says nothing about what happens when the value is nil.  Please fix
> that.  In particular, please point out that the nil behavior was the
> default behavior before Emacs version 23.blah.

Fixed, thanks.