Temporarily disable libyuv tests on i686
Temporarily disable libyuv tests on i686

Since the recent gtest update in the SDK one of tests
(libyuvTest.Ssim) as been mysteriously failing on i686
only.

TBR=bradnelson
BUG=434821

Review URL: https://codereview.chromium.org/745813002

Schibum/naclports,yeyus/naclports,yeyus/naclports,Schibum/naclports,yeyus/naclports,Schibum/naclports,Schibum/naclports,yeyus/naclports,Schibum/naclports,Schibum/naclports,yeyus/naclports,yeyus/naclports