tweak qemu_notify_event

Instead of testing specially next_cpu in host_alarm_handler, just do
that in qemu_notify_event.  The idea is, if we are not running (or
not yet running) target CPU code, prepare things so that the execution
loop is exited asap; just make that clear.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

vl.c

@@ -1055,13 +1055,6 @@ static void host_alarm_handler(int host_signum)
                            qemu_get_clock(host_clock))) {
 
         t->expired = alarm_has_dynticks(t);
-
-#ifndef CONFIG_IOTHREAD
-        if (next_cpu) {
-            /* stop the currently executing cpu because a timer occured */
-            cpu_exit(next_cpu);
-        }
-#endif
         t->pending = 1;
         qemu_notify_event();
     }
@@ -3364,6 +3357,9 @@ void qemu_notify_event(void)
     if (env) {
         cpu_exit(env);
     }
+    if (next_cpu && env != next_cpu) {
+	cpu_exit(next_cpu);
+    }
 }
 
 void qemu_mutex_lock_iothread(void) {}