Merge change 2717 into donut

* changes:
  build images with minigzip instead of system gzip
tree: 3f4c50670b97fc4c1f1105ae6d7b83470787f323
  1. core/
  2. libs/
  3. target/
  4. tools/
  5. buildspec.mk.default
  6. cleanspec.mk
  7. envsetup.sh