The idea is to add a bot and an empty target such that we invoke
gcc empty_main.cc with Chromium's build flags.
The intention is to catch clang-only flags that break the gcc
build.
Bug: chromium:776284
Change-Id: I9e7dc21b15e0903c813de31d4b0731515e6e4426
Reviewed-on: https://chromium-review.googlesource.com/876010
Commit-Queue: Patrik Höglund <phoglund@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#536040}
