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: I557efff8d77be006eb3e3db6a1553e99b6ecb2cb