[patch] Also handle ConstantAggregateZero when optimizing vpermilvar*

[Jim Grosbach]

LGTM.

On Apr 29, 2014, at 2:31 PM, Rafael Espíndola <rafael.espindola at gmail.com> wrote:

> The attached patch completes the vpermilvar* optimization by handling
> ConstantAggregateZero.
> 
> Cheers,
> Rafael
> <t.patch>