Update build-tools to ab/3258631

Major update is ckati merge from upstream. (With MAKEFLAGS now cleared
in build/ so that https://github.com/google/kati/issues/89 doesn't cause
us to revert again)

build sha 6b363e24
build/kati sha e1de29e5
build/soong sha 42d1ba2d
external/ninja sha ee767f71

Change-Id: Idaf4867058111184f2ce633ed0afe21a90af1f8c
14 files changed
tree: 8860e0d20d80a5e15b33f1a30a40b7c5c36922ce
  1. darwin-x86/
  2. linux-x86/
  3. build-prebuilts.sh