bug#12314: 24.2.50; `add-to-history': use `setq' with `delete'

[Eli Zaretskii]

> From: "Drew Adams" <drew.adams@oracle.com>
> Cc: <cyd@gnu.org>, <12314@debbugs.gnu.org>
> Date: Sat, 8 Sep 2012 09:25:08 -0700
> 
> Go for it.  I suggest mentioning something like this in node `Modifying Lists'
> (and then cross-ref'ing that node from other nodes about functions that are
> destructive of list structure):

Why is it even necessary to talk about destructive modifications, if
we are to advise to assign the result anyway?