Merge branch 'stable-2.16' into stable-3.0

* stable-2.16:
  Upgrade bazlets to latest stable-2.16 to build with 2.16.21 API
  Upgrade bazlets to latest stable-2.15 to build with 2.15.19 API
  Upgrade bazlets to latest stable-2.14 to build with 2.14.21 API

Change-Id: Ia8da3a5ecf730c65258caceded7bb9ed3e2465b7