Update kernel-build-tools to ab/6669862

https://ci.android.com/builds/branches/aosp_kernel-build-tools/grid?head=6669862&tail=6669862

Bug: 160825200
Test: treehugger
Change-Id: I5b4522a6502fd4f185ec7f610292a94c81defd32
4 files changed
tree: 91ad9f0e93e9cb5bae26da466d21191936dda53e
  1. linux-x86/
  2. build-prebuilts.sh
  3. manifest.xml
  4. update-prebuilts.sh