bug#21275: 24.5; Selection deleted with electric pair mode in cc mode

[Drew Adams <drew.adams@oracle.com>]

> > +(defun delete-selection-uses-region-p ()
> 
> The way I read it, this name says "a function which tells us if
> delete-selection uses the region".

No idea what this is all about, but if this is for
`electric-pair-mode' and not for `delete-selection-mode' then
the name should reflect that - call it `electric-pair-SOMETHING'.

Is this something that `delete-selection-mode' needs?  Or is it
for something else?

> > +  "Return non-nil when the current command uses the region.

What does it mean for a command to "use the region"?

> It's not about "the current command" but about self-insert-command
> (which may be the current command or may be called by the current
> command).

What does it mean for such a command (or any other command) to
"use the region"?  That info should presumably be in the doc string.