avbtool: add support for signing helper.
am: 4e55279b45

Change-Id: I27540e813257fdc660336d91c3dcfc48b1f85492
tree: ccce8cac2aa9345acb5e7d6891bc1ad01d5c57f0
  1. boot_control/
  2. libavb/
  3. libavb_ab/
  4. test/
  5. Android.mk
  6. avbtool
  7. LICENSE
  8. README