Comment # 5 on bug 91193 from Michel Dänzer

(In reply to Sebastian Parborg from comment #4)
> I'm guessing that this is just a temporary workaround?

No, I think it's the proper fix. TGSI_SEMANTIC_CLIPDIST values are also passed
to the pixel shader as a varying, so they need to be counted here.

I'll submit the patch to the mesa-dev mailing list for review.