Monitor: Introduce monitor_get_cpu_index()

Returns 'cur_mons's CPU index. A future commit will use it.
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

monitor.c

@@ -794,6 +794,11 @@ static CPUState *mon_get_cpu(void)
     return cur_mon->mon_cpu;
 }
 
+int monitor_get_cpu_index(void)
+{
+    return mon_get_cpu()->cpu_index;
+}
+
 static void do_info_registers(Monitor *mon)
 {
     CPUState *env;

monitor.h

@@ -58,6 +58,7 @@ void monitor_printf(Monitor *mon, const char *fmt, ...) GCC_FMT_ATTR(2, 3);
 void monitor_print_filename(Monitor *mon, const char *filename);
 void monitor_flush(Monitor *mon);
 int monitor_set_cpu(int cpu_index);
+int monitor_get_cpu_index(void);
 
 typedef void (MonitorCompletion)(void *opaque, QObject *ret_data);