bug#28103: M-x customize should use fill-column

[Charles A. Roelli]

>From emacs -q:

M-x load-library eshell RET
M-x customize-variable eshell-modules-list RET

gives something like this:

Eshell Modules List:
[X] eshell-alias -- Command aliases

Command aliases allow for easy definition of alternate commands.
 
[X] eshell-banner -- Login banner

This sample module displays a welcome banner at login.
It exists so that others wishing to create their own Eshell extension
modules may have a simple template to begin with.
 
[X] eshell-basic -- Basic shell commands

The "basic" code provides a set of convenience functions which
are traditionally considered shell builtins.  Since all of the
functionality provided by them is accessible through Lisp, they are
not really builtins at all, but offer a command-oriented way to do the
same thing.

[...]

Which lines are too long?

> From: Yegor Timoshenko <yegortimoshenko@gmail.com>
> Date: Tue, 15 Aug 2017 20:05:46 +0000
> 
> 
> 
> Hello! This is an enhancement request.
> 
> M-x customize sometimes produces very long lines (for example, try 
> customizing eshell-modules-list). It'd be nice if M-x customize honored 
> `fill-column` when pretty-printing.