g10: Add support for TRUST_NEVER.
* g10/pkclist.c (do_we_trust): Handle TRUST_NEVER, which can be returned by the TOFU trust model. (do_we_trust_pre): Print a different message if TRUSTLEVEL is TRUST_NEVER. (check_signatures_trust): Improve comment.
- Signed-off-by: Neal H. Walfield <neal@g10code.com>