Merge branch 'stable-3.1' * stable-3.1: Upgrade bazlets to latest stable-2.16 to build with 2.16.18 API Bump Bazel version to 3.1.0 Bump Bazel version to 3.0.0 Change-Id: I45061ed0d913d6f33c8dcfed6a3b83b7efd57c3b