gpg: Keep the trust DB up to date for the tofu and tofu+pgp models.
* g10/trustdb.c (init_trustdb): Recognize tofu and tofu+pgp as possibly saved trust models. Also register the ultimately trusted keys if the trust model is tofu or tofu+pgp. (check_trustdb): Don't skip if the trust model is tofu or tofu+pgp. (update_trustdb): Likewise. (tdb_check_trustdb_stale): Likewise. (validate_keys): If the trust model is TOFU, just write out the ultimately trusted keys.
- Signed-off-by: Neal H. Walfield <neal@g10code.com>