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

Change-Id: Id516de13a529a6817527f742f75e8ed16e9e9560
tree: 6487cb699dce5fb1f9f35c4b30f3be55224d9be4
  1. darwin-x86/
  2. linux-x86/
  3. build-prebuilts.sh
  4. manifest.xml