src: improve get_card_readers logic
src: improve get_card_readers logic

- Use SCARD_AUTOALLOCATE if available. It avoids one extra call to
  SCardListReaders.
- If it's not available handle SCARD_E_INSUFFICIENT_BUFFER error by
  retrying get_card_readers.

santigimeno/node-pcsclite,santigimeno/node-pcsclite,santigimeno/node-pcsclite