qom/cpu: Add throttle_thread_scheduled member

Extracts the member out of commit 2adcc85d407c1ab985f5abed808c78dbb84f4773

qemu/include/qom/cpu.h

@@ -269,6 +269,11 @@ struct CPUState {
     uint32_t can_do_io;
     int32_t exception_index; /* used by m68k TCG */
 
+    /* Used to keep track of an outstanding cpu throttle thread for migration
+     * autoconverge
+     */
+    bool throttle_thread_scheduled;
+
     /* Note that this is accessed at the start of every TB via a negative
        offset from AREG0.  Leave this field at the end so as to make the
        (absolute value) offset as small as possible.  This reduces code