scd:nks: Handle APP_READKEY_FLAG_INFO.
* scd/app-nks.c (keygripstr_from_pk_file): Fix ignored error. (get_nks_tag): New. (do_learn_status_core): Use it. Make sure not to mange the KEYPAIRINFO line if no usage is known. (do_readkey): Output the KEYPAIRINFO for the keygrip case.
Note that this only handles the most common case of providing a
keygrip. $AUTHKEYID and ODLM are not yet supported.
- Signed-off-by: Werner Koch <wk@gnupg.org>