Update build-tools to ab/3050982 am: 5a966750a5
am: 1b9bea742e

Change-Id: I997cfc5975ecee0a8b44914d879a5f5a398bf8b2
tree: 3c6072889457e0ff890ebd6d2dd33671cebc1cd2
  1. darwin-x86/
  2. linux-x86/
  3. build-prebuilts.sh