bug#31039: 27.0.50; allow silencing auto-save

[Federico]

Thanks Eli, I've taken a look at the commit and noted the corrections
you listed. Also, good to know about the copyright assignment.

On Sat, Aug 11, 2018 at 7:11 AM, Eli Zaretskii <eliz@gnu.org> wrote:
>> Date: Sat, 11 Aug 2018 12:31:34 +0300
>> From: Eli Zaretskii <eliz@gnu.org>
>> Cc: 31039-done@debbugs.gnu.org, npostavs@gmail.com, aaronjensen@gmail.com
>>
>> A few minor nits for your future contributions:
>>
>>   . For changes in the manuals, the name of the node where the change
>>     is done should be mentioned in parentheses, as if it were a
>>     function.
>>   . Please make sure the NEWS entries are filled according to the
>>     default setting of fill-column (use M-q to do that).
>>   . It is preferable to explicitly mention the new functions/variables
>>     in the log entries for NEWS and the manuals.
>
> Sorry, 2 more:
>
>   . Always mention the bug number in the log entry.
>   . When you add a new customizable option, always mark it with the
>     first Emacs version where the option will appear, in this case
>     27.1.
>
> Thanks.