Update build-tools to ab/4051621 am: 01920bfb3c am: 6b9562be77 am: e8ea100ba7
am: b246e8a436

Change-Id: I88f74aafed14e981f58731f1ac40d8fa504ecbfb
tree: 99e76231fab7582e6952ca8dc170d04f857822de
  1. darwin-x86/
  2. linux-x86/
  3. build-prebuilts.sh
  4. manifest.xml