Summary:
Currently we have `-O3` hardcoded inside our BUCK target files, this will allow us afterwards to remove that.
Follow up commit will also add `-DNDEBUG` which will disable `assert` in release builds.
Reviewed By: emilsjolander
Differential Revision: D6592024
fbshipit-source-id: f541ee8728ff44db8e31885f2085dc036a400f70
