message: Don't remove incremental cache for sysroot building
  This more than halves compilation time for the sysroot
diff: @@ -3,7 +3,8 @@ set -e
  cd $(dirname "$0")
  # Cleanup for previous run
  -cargo clean
  +# v Clean target dir except for build scripts and incremental cache
  +rm -r target/*/{debug,release}/{build,deps,examples,libsysroot*,native} || true
  rm Cargo.lock 2>/dev/null || true
  rm -r sysroot 2>/dev/null || true
  