lint: add shebang checker

BUG=None
TEST=`./cbuildbot/run_tests` passes

Change-Id: Ic46eaf13f7fe910938353baeaa6301002c6c68b3
Reviewed-on: https://chromium-review.googlesource.com/243773
Reviewed-by: Anatol Pomazau <anatol@google.com>
Trybot-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
2 files changed