Merge branch 'stable-2.15'

* stable-2.15:
  Update to latest bazlets on stable-2.15
  Update bazlets to latest revision on stable-2.14
  Upgrade to latest bazlets on stable-2.14
  Use latest bazlets

No-op merge done with `-s ours`.

Change-Id: I1f35abdb38cf4ded0cc3e474f74f77a180f33ec3