Merge changes Idf64b96b,Ie717089d into nyc-dev
am: c52269542a  -s ours

* commit 'c52269542a652250c011018f602d1db346f6cd68':
  Base isDexOptNeeded result on OatFileAssistant::IsUpToDate.
  Only compile dex files if they are not up to date.

Change-Id: I921009d2dd104ef2498c396827803a38e1bec828