cbuildbot_config: Create placeholder Project SDK build.

Create a placeholder Project SDK build that we can use while
developing the code to handle this new build type. Mostly creating
now, so tryjobs can be used.

BUG=brillo:49
TEST=Unittests

Change-Id: I495cfe06e08b8efce4cc6253fd43477940f2270c
Reviewed-on: https://chromium-review.googlesource.com/243601
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Don Garrett <dgarrett@chromium.org>
3 files changed