Add src-side configs for CI and optional try simplechrome lto bot.

The current amd64-generic builder has thin-lto and cfi disabled by default
for build cycle time reasons. Chromeos-chrome ebuilds use them both however,
so changes might slip in that break the ebuild but pass on the cq.

This will add a CI bot (and an optional trybot) that has them both enabled.

Bug: 924192
Change-Id: I371e4c6606c0e2e28112750add47208e9dcfd899
Reviewed-on: https://chromium-review.googlesource.com/c/1431515
Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625404}
6 files changed