am 150e16ea: Merge remote-tracking branch \'aosp/upstream\'

* commit '150e16ea': (162 commits)
  Support go 1.5
  Fix bootstrap package build stage default
  Support a separate build directory
  Switch bootstrap.BinDir to a StaticVariable
  Use three stage builds
  Enhance bootstrap stage selection
  Add test suite for bootstrapping
  Switch to custom-built ninja v1.6.0
  Migrate to container-based travis infrastructure
  Fix running travis on forked repos
  Require ninja 1.6.0, remove workaround
  Don't print module header if nothing is defined
  Fix a sub-Blueprints deps bug.
  Add deep Copy() for parser types
  Refactor parsing to allow reuse
  Add convenience methods to Comment objects
  Add self-documenting support
  Support filtering nested structures by tag
  Add option to build and run tests during bootstrap
  Create internal bootstrap Config struct
  ...