scd: No hard lock-up when apdu_connect never returns.
* scd/app.c (new_card_lock): New. (select_application): Scanning is serialized by NEW_CARD_LOCK. For app_new_register, we hold the W-lock. (initialize_module): Initialize NEW_CARD_LOCK.
- GnuPG-bug-id: T7402
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>