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

[Eli Zaretskii]

> Date: Wed, 4 Mar 2020 16:42:40 +0000 (GMT)
> From: ndame <emacsuser@freemail.hu>
> 
> I was working on a big text data file and I used flush-lines and instead of 
> it saying
> nothing it would have been nice to know how many lines were flushed by it.
> 
> The same goes for keep-lines. It should say in a message how many lines it 
> flushed
> while keeping the matching lines.

Upgrade to Emacs 27, this happens there already.