am 3938ab25: am 1b6d0a65: allow prebuilts to specify LOCAL_CERTIFICATE so they can be resigned

Merge commit '3938ab2572e7c9d5894975c0076b271b2846faa9'

* commit '3938ab2572e7c9d5894975c0076b271b2846faa9':
  allow prebuilts to specify LOCAL_CERTIFICATE so they can be resigned