bump atc
bump atc

[finishes #109381498]

Submodule src/github.com/concourse/atc bf8a9ce..02a0c43:
  > optimize Destroy() for pipelines
  > use same scanBuild() everywhere in db package

Signed-off-by: Corbin Halliwill <38cf05332854d0c00b392ad9da3fb5cec295aa83@pivotal.io>

concourse/concourse,cjcjameson/concourse,cjcjameson/concourse,zachgersh/concourse,zachgersh/concourse,zachgersh/concourse,concourse/concourse,cjcjameson/concourse,concourse/concourse,concourse/concourse,concourse/concourse