When building Debug IRT, use -O2 instead of -O0 for the frontend
When building Debug IRT, use -O2 instead of -O0 for the frontend

This keeps the IRT from growing beyond its 6 MB text segment limit,
while not affecting the incremental build time much (since only the
compiler target libraries are built as bitcode in any case).

BUG=none (debug IRT expanded beyond its 6M limit and blocked the
NaCl roll into chrome)

R=jvoung@google.com, mseaborn@chromium.org

Review URL: https://codereview.chromium.org/27557006

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@12270 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

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