annotated_run.py: Fix dependency on "build/".
annotated_run.py: Fix dependency on "build/".

`annotated_run.py` currently expects the Gclient spec to contain a
"build/" checkout. CrOS waterfalls don't, and it is causing
`annotated_run.py` to soft-fail in "update_scripts".

Also fix _run_command not forwarding **kwargs.

BUG=None
TEST=None
R=iannucci@chromium.org

Review URL: https://codereview.chromium.org/1493203002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@297818 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build