bug#19423: 25.0.50; incompatible change to `make-obsolete' - added 3rd arg should be optional

[Drew Adams]

> > You should look at the byte-compiler warning that the user sees.
> 
> It's a warning, not an error. The code will work.

The warning is blatantly incorrect - the 3rd arg is not required.
It misleads.  There is no need for such a "warning" - nothing to
warn users about, since the argument is optional.  It serves
no useful purpose.  It causes harm by lying to users, confusing
and misleading them.

There is no good reason not to fix this now.  And no reason at
all to close it.