Build PNaCl debug/fastbuild IRT with O2 instead of O0
Build PNaCl debug/fastbuild IRT with O2 instead of O0

Using O0 is causing a build failure that may be a problem with the
toolchain or the user code; in either case, work around it for now by
going back to O2 for PNaCl builds.

R=bradnelson@google.com
BUG= https://code.google.com/p/chromium/issues/detail?id=388035

Review URL: https://codereview.chromium.org/475893002

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@13622 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

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