scd: New option --pcsc-shared.
* scd/scdaemon.h (opt): Add field opcsc_shared. * scd/scdaemon.c (opcscShared): New. (opts): Add "--pcsc-shared". (main): Set flag. * scd/apdu.c (connect_pcsc_card): Use it. (pcsc_get_status): Take flag in account. * scd/app-openpgp.c (verify_chv2): Do not auto verify chv1 in shared mode.
This option should in general not be used. The patch tries to limit
bad effects but using shared mode is somewhat dangerous depending on
the other PC/SC users.
(cherry picked from commit 5732e7a8e97cebf8e850c472e644e2a9b040836f)