[infra] Make most builds idempotent

Change-Id: I084645a46feda183747e9d7fc3b40b1aa56c5f78
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/211103
Commit-Queue: Eric Boren <borenet@google.com>
Reviewed-by: Ben Wagner aka dogben <benjaminwagner@google.com>
14 files changed