[RenderScript] Add ScriptGroup2 API for RenderScript Support Lib.

  - For now, the new ScriptGroup2 API is only available for API 23+
    native mode, or pure compat mode.
  - Incremental Support Mode (hybrid mode) will be added in another CL.

Change-Id: I268e721e8724d51e54ab3f80e7762da4ddac4ff9
4 files changed