Only pass -O2 as a link option for pnacl test pexes.
Only pass -O2 as a link option for pnacl test pexes.

GCC ignores -O0 / -O2 on the link line, dropping it.
Activating -O2 for the link line for pnacl test pexes only.

BUG=https://code.google.com/p/chromium/issues/detail?id=388035
TEST=None
R=dschuff@chromium.org

Review URL: https://codereview.chromium.org/466313006

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@13615 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

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