Add hot_add_cpu hook to QEMUMachine

Hook should be set by machines that implement CPU hot-add
via cpu-add QMP command.
Signed-off-by: NIgor Mammedov <imammedo@redhat.com>
Reviewed-by: NEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NAndreas Färber <afaerber@suse.de>

include/hw/boards.h

@@ -22,12 +22,15 @@ typedef void QEMUMachineInitFunc(QEMUMachineInitArgs *args);
 
 typedef void QEMUMachineResetFunc(void);
 
+typedef void QEMUMachineHotAddCPUFunc(const int64_t id, Error **errp);
+
 typedef struct QEMUMachine {
     const char *name;
     const char *alias;
     const char *desc;
     QEMUMachineInitFunc *init;
     QEMUMachineResetFunc *reset;
+    QEMUMachineHotAddCPUFunc *hot_add_cpu;
     BlockInterfaceType block_default_type;
     int max_cpus;
     unsigned int no_serial:1,