do not use qemu_event_increment outside qemu_notify_event

qemu_notify_event in the non-iothread case is only stopping the current
CPU.  However, if the CPU is idle and the main loop is in the select
call then a call to qemu_event_increment is needed too (as done in
host_alarm_handler).  Since in general one doesn't know whether the CPU
is executing or not, it is a safe bet to always do qemu_event_increment.

Another way to see it: after this patch qemu_event_increment is the
"common part" of qemu_notify_event for both the CONFIG_IOTHREAD and
!CONFIG_IOTHREAD cases, which makes sense.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

vl.c

@@ -1053,7 +1053,7 @@ static void host_alarm_handler(int host_signum)
                            qemu_get_clock(rt_clock)) ||
         qemu_timer_expired(active_timers[QEMU_CLOCK_HOST],
                            qemu_get_clock(host_clock))) {
-        qemu_event_increment();
+
         t->expired = alarm_has_dynticks(t);
 
 #ifndef CONFIG_IOTHREAD
@@ -3360,6 +3360,7 @@ void qemu_notify_event(void)
 {
     CPUState *env = cpu_single_env;
 
+    qemu_event_increment ();
     if (env) {
         cpu_exit(env);
     }