scd: acquire lock in new_reader_slot.
* scd/apdu.c (new_reader_slot): Acquire lock. (open_ct_reader, open_pcsc_reader_direct, open_pcsc_reader_wrapped) (open_ccid_reader, open_rapdu_reader): Release lock. (lock_slot, trylock_slot, unlock_slot): Move more to the top.
Fixes a test case of:
No libpcsclite1 installed. Run gpg-agent Run command "gpg-connect-agent learn /bye" with no card/token Sometimes it fails: ERR 100663356 Not supported <SCD> While it should be always: ERR 100663404 Card error <SCD>
(cherry picked from commit 4f557cb9c2ebe274d6aacc60a09cd919055d01ed)
Resolved conflicts:
scd/apdu.c: pth/npth changes. Move lock helpers to the top.
Take care of removed pcsc_no_service.