bot_update does a git clean -dff before each run, so we were redownloading all the utilities on each run. This should make the bots only download them when the change. (Chromium's setup is similar.) Change-Id: I7eb83217761ceabe58b5480242a7df93d9bfaa52 Reviewed-on: https://boringssl-review.googlesource.com/12561 Commit-Queue: David Benjamin <davidben@google.com> Reviewed-by: Adam Langley <agl@google.com>kris/onging/CECPQ3_patch15