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
  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: I4e9950901ca25a62849f5f6261dc2f5b4bfc4a7f