Update clang-tools to ab/6137988 am: d9fe13dddc am: 6edfe3af34 am: 257b5fd202

Change-Id: I0e97b3a8b8c5e11b05807ffdb854beb2d7fdd6ed
tree: 6487cb699dce5fb1f9f35c4b30f3be55224d9be4
  1. darwin-x86/
  2. linux-x86/
  3. build-prebuilts.sh
  4. manifest.xml