I noticed current autoninja does not upload build log in failed build.

Change-Id: Ie58646b483e130769ad22113953c0b95b3145548
Reviewed-on: https://chromium-review.googlesource.com/c/1441892Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>