agent: Handle USAGE information in KEYINFO.
* agent/agent.h (struct card_key_info_s): Add USAGE field. * agent/call-scd.c (card_keyinfo_cb): Parse USAGE field. Allow optional SERIALNO, IDSTR, and USAGE fields. Fix releasing on possible allocation error.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>