Merge branch 'stable-2.15'

* stable-2.15:
  Upgrade bazlets to latest stable-2.15 to build with 2.15.12 API
  Upgrade bazlets to latest stable-2.14 to build with 2.14.19 API

Change-Id: Icdb68dac8b2ec5ef7f27ea0568cee9a07b82989f