Merge branch 'stable-3.0' into stable-3.1

* stable-3.0:
  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
  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: Ie5f61a36b6c0df4cd21da11536e95b138c32cf07