bug#10868: 24.0.93; `comment-style' needs to be explained

[Chong Yidong]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> OK, here's the problem, and here's a patch.
>> 2012-02-23  Lawrence Mitchell <wence@gmx.li>
>> * lisp/newcomment.el: Autoload comment-styles (Bug#3370).
>
> Another fix is to remove the ;;;###autoload from comment-style.
> If that doesn't introduce other problems, it's a better solution.

The docstring of comment-region refers to comment-style, so removing the
autoload of comment-style brings us back to square one.

I added an autoload for comment-styles.