g10: Add a convenience function for checking if a key is a primary key
* g10/keydb.h (pk_is_primary): New function. * g10/tofu.c (get_trust): Use it. (tofu_register_signature): Likewise. (tofu_register_encryption): Likewise. (tofu_set_policy): Likewise. (tofu_get_policy): Likewise.
- Signed-off-by: Neal H. Walfield <neal@g10code.com>