Don't try to listen on the scard socket if it isn't there

If the scard local socket can't be created, there's no point
in trying to listen on it. This will just fill the chansrv log
file with errors.

sesman/chansrv/devredir.c

@@ -803,8 +803,7 @@ devredir_proc_client_core_cap_resp(struct stream *s)
 
             case CAP_SMARTCARD_TYPE:
                 LOG_DEVEL(LOG_LEVEL_DEBUG, "got CAP_SMARTCARD_TYPE");
-                g_is_smartcard_redir_supported = 1;
-                scard_init();
+                g_is_smartcard_redir_supported = (scard_init() == 0);
                 break;
         }
         xstream_seek(s, cap_len);