am 31c9763a: merge in KQS81M

* commit '31c9763a1b5f45ee51cef272244a58fb1115945a':
  Make inlined CAS32 loop until store is successful if values match.
  Revert "Fix CAS intrinsic to clear exclusive if values don't match."
  Fix ImageHeader.IsValid
  Add flock(2)ing on dex-cache files to prevent races