Fix compilation when smartcard support is disabled

The addition of smartcard control to the controller doesn't handle
the case when smartcard support is disabled at compile time. When
this is the case, this causes compile errors.

client/application.cpp

@@ -1675,10 +1675,12 @@ void Application::set_title(const std::string& title)
     }
 }
 
+#ifdef USE_SMARTCARD
 void Application::enable_smartcard(bool enable)
 {
     _smartcard_options->enable = enable;
 }
+#endif
 
 bool Application::is_key_set_pressed(const HotkeySet& key_set)
 {

client/application.h

@@ -227,7 +227,9 @@ public:
     void external_show();
     void connect();
     void switch_host(const std::string& host, int port, int sport, const std::string& cert_subject);
+#ifdef USE_SMARTCARD
     void enable_smartcard(bool enable);
+#endif
 
     const PeerConnectionOptMap& get_con_opt_map() {return _peer_con_opt;}
     const RedPeer::HostAuthOptions& get_host_auth_opt() { return _host_auth_opt;}

client/controller.cpp

@@ -334,9 +334,11 @@ bool ControllerConnection::handle_message(ControllerMsg *hdr)
     case CONTROLLER_DELETE_MENU:
         _handler->delete_menu();
         break;
+#if USE_SMARTCARD
     case CONTROLLER_ENABLE_SMARTCARD:
         _handler->enable_smartcard(value);
         break;
+#endif
     case CONTROLLER_SEND_CAD:
     default:
         LOG_ERROR("Ignoring an unknown/SEND_CAD controller message %u", hdr->id);

client/controller.h

@@ -50,7 +50,9 @@ public:
     virtual Menu* get_app_menu() = 0;
     virtual void set_menu(Menu* menu) = 0;
     virtual void delete_menu() = 0;
+#ifdef USE_SMARTCARD
     virtual void enable_smartcard(bool enable) = 0;
+#endif
 };
 
 class Controller : public NamedPipe::ListenerInterface {