agent: Fix use of imported but unprotected openpgp keys.
* agent/agent.h (PRIVATE_KEY_OPENPGP_NONE): New. * agent/command.c (do_one_keyinfo): Implement it. * agent/findkey.c (agent_key_from_file): Ditto. (agent_key_info_from_file): Ditto. (agent_delete_key): Ditto. * agent/protect.c (agent_private_key_type): Add detection for openpgp "none" method.
- Signed-off-by: Werner Koch <wk@gnupg.org>