hooks/pre-commit: check for cycles in dependencies
We need only to consider newly added dependencies. For each of these deps we
need to check if there is a path from this dep to the current HEAD.
We use recursive_dep() for this task. Even if recursive_dep() uses a DFS
traversal it will not run into an endless loop if there would be a cycle,
because recursive_dep() takes .topdeps only from committed trees. And we
require that the committed dependency graph has no cycles.
Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>