Introduce --multi-dex option in dx.

Add --multi-dex options to dx command line to allow the generation of
several dex files when method index limit is about to be reached.
Also add
  --main-dex-list allowing to force some classes in the main dex.
  --minimal-main-dex to keep in main edx only classes specified by
  --set-max-idx-number to set an arbitrary idx limit for the

Change-Id: I57d0860b6156e53355e08151b64c1320b7984004
9 files changed