[polly] Add diagnostic remark for ReportVariantBasePtr

[Tobias Grosser]

On 26/06/2014 15:38, Andreas Simbuerger wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> At the moment the DebugLoc is derived from the BaseValue.
> I'm not 100% sure if the resulting DebugLoc corresponds to the
> A or the (A->b) BaseValue.

Possibly A->b.

> As far as I can tell, both would map to the same source location in
> the debug-metadata.

The caret diagnostic points for me at the beginning of the line. This is 
good. If we ever figure out how to get the precise column location, that 
would be amazing.

Also, I figured that I need to add -polly-detect-track-failures to get
the missed optimizations output. As the possibly expensive formatting is 
done afterwards, I wonder if it would make sense to enable it by default?

Cheers,
Tobias