new --exclude-from=FILE option

[maurerdietmar]

Exclude files matching patterns listed in FILE.

Signed-off-by: Dietmar Maurer [email protected]

[poettering]

btw, ideally we'd serialize all info we use for putting together an image into the caidx/catar. This means in the long run any additional exclusion lists should probably serialized somehow into both too. That way things become more reproducible, as this means you can validate a tree against a serialization and need no other info.