Update build-tools to ab/3991694 am: f17ec1f7a0 am: 50ad5fe35b am: 192532aa04
am: a48ee5320d

Change-Id: Iff441f3f6dffa23d44fbc41292314b76afb635d4
tree: 956be210360dfb1ae794f9d5b56124131f054378
  1. darwin-x86/
  2. linux-x86/
  3. build-prebuilts.sh
  4. manifest.xml