Merge branch 'stable-3.1'

* stable-3.1:
  Upgrade bazlets to latest stable-3.1 to build with 3.1.6 API
  Upgrade bazlets to latest stable-3.0 to build with 3.0.10 API
  Upgrade bazlets to latest stable-2.16 to build with 2.16.21 API

Change-Id: I8e52da96a08653a8d1f69e85a4fe93bbeae33b7e