Add back one exclusion to libcxx test known failures.
Add back one exclusion to libcxx test known failures.

It was mistakenly removed in the last update.

R=jfb@chromium.org

Review URL: https://codereview.chromium.org/645953002

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@13885 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client