Android p preview 4
Merge changes from topic "metalava"

* changes:
  Add metalava dependencies
  Add AGP 3.2.0 alpha16 prebuilts.
tree: aee42bacd2f099fabde39d75101a9065af074114
  1. androidx/
  2. com/
  3. net/
  4. org/
  5. .gitignore
  6. Android.bp