bug#19844: 25.0.50; No flyspell with erc

[Eli Zaretskii]

> Date: Thu, 12 Feb 2015 13:23:32 +0100
> From: Cédric Chépied
>       <cedric.chepied@gmail.com>
> 
> 
> Since a couple of day, flyspell doesn't work anymore in erc buffers. I'm on
> emacs master branch. In the function erc-spelling-flyspell-verify, 
> flyspell-word
> variable is not defined. I think this was a global variable in flyspell code
> which doesn't exist anymore.

My crystal ball says this is related to the following commit:

  commit ebbdc6c30dc883ffb9ddb53c0263ef325d251903
  Author: Stefan Monnier <monnier@iro.umontreal.ca>
  Date:   Wed Feb 4 14:43:47 2015 -0500

      * lisp/textmodes/flyspell.el: Use lexical-binding and cl-lib.

      (mail-mode-flyspell-verify): Fix last change.
      (flyspell-external-point-words, flyspell-large-region):
      Avoid add-to-list on local vars.