Merge changes I5c891dc1,Ie717089d am: f736a55d84
am: 7698da6718

* commit '7698da6718b9e667434fb8a66af3d8e26330bed0':
  Base isDexOptNeeded result on OatFileAssistant::IsUpToDate.
  Only compile dex files if they are not up to date.

Change-Id: Idfa67b6fa5c14c930bb72fa81d05913546552a5c