Merge changes from topic 'class-loader-context' into oc-mr1-dev

* changes:
  Stop using the runtime classpath in dex2oat
  Do not pass --runtime-arg -classpath in dex2oat_test
  Do not pass --runtime-arg -classpath to dex2oat in dex fuzz
  Pass the class loader context to dex2oat when optimizing at runtime