Update build-tools to ab/3991694 am: f17ec1f7a0
am: 50ad5fe35b

Change-Id: I419b6b9007a34c112f2f604262b853221ef75df1
tree: 956be210360dfb1ae794f9d5b56124131f054378
  1. darwin-x86/
  2. linux-x86/
  3. build-prebuilts.sh
  4. manifest.xml