bug#39908: 26.2; flush-lines and keep-lines should say how many lines were flushed

[Noam Postavsky]

ndame <emacsuser@freemail.hu> writes:

> I guess most users use it to remove whole lines most of the time, so the match
> is usually not split across lines, therefore the number of deletions in these 
> cases is
> equal to the number of deleted lines.

That would apply to flush-lines (and I think the current counting code
does make that assumption), but not keep-lines.  For keep-lines, if
matches don't span lines, then the number of lines is equal to the
number of lines kept, rather than lines deleted.  And there is less
usefulness in reporting lines kept, since the user can see that directly
(or use M-= (count-words-region)).