bug#13312: 24.3.50; delete selection mode not killing on overwrite

[Drew Adams]

> > Isn't there a better way?
> 
> I think (run-hook-with-args-until-success 'self-insert-uses-region-
> functions) could be moved to the body of `delete-selection-helper'.
> Then the users again will enjoy the simplicity of
>     (put 'self-insert-command 'delete-selection t)
> and (put 'self-insert-command 'delete-selection 'kill)

That sounds good.  Thank you, Juri.  I didn't check that things work
well with that change, but the description sounds right.

> The first hunk of my patch fixes the reported bug.

Please install that part, at least.  Not sure what the rest does,
but why not handle it as a separate bug fix?