Revert the change to enable validator_arm tests on x86-64
Revert the change to enable validator_arm tests on x86-64

the clang build warning issue has been fixed, so it should be safe to
reland this.

R=jfb@chromium.org

BUG= none
TEST= none

Review URL: https://codereview.chromium.org/23559007

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@12089 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

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