Add Subzero to x86-32 specbot testing.
Add Subzero to x86-32 specbot testing.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4092
R=jfb@chromium.org

Review URL: https://codereview.chromium.org/1047543002

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