[m-rev.] diff: Avoid gcc warning about tautological comparison in test case.

[Peter Wang]

On Fri, 19 Oct 2018 17:33:48 +1100 (AEDT), "Zoltan Somogyi" <zoltan.somogyi at runbox.com> wrote:
> 
> The fix seems obvious: make simplify_improve_builtin_compare
> look for situations where a value is compared with itself,
> and replace compare(Result, X, X) with Result = (=).
> 
> Peter, do you want to do it, or should I?

Ok, I'll have a look at it then.

Peter