[ninjalog] don't upload ninja log of no-op build
[ninjalog] don't upload ninja log of no-op build

Check timestamp of .ninja_log before upload and don't upload if mtime is very old.

Bug: 900161
Change-Id: I0cf00ae29e23a9f609564e4c12b4b518320ca23a
Reviewed-on: https://chromium-review.googlesource.com/c/1404611
Commit-Queue: Shinya Kawanaka <2933a093a0e95183ceb652f66f20d25372736927@chromium.org>
Reviewed-by: Shinya Kawanaka <2933a093a0e95183ceb652f66f20d25372736927@chromium.org>
Auto-Submit: Takuto Ikuta <71927f930fca81015e0f496c65cd126ab1a692e3@chromium.org>

CoherentLabs/depot_tools,CoherentLabs/depot_tools