event notifier: Fix setup for win32

The event notifier state is only reset by test_and_clear. But we created
the windows event object with auto-reset, which subtly swallowed events.
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

event_notifier-win32.c

@@ -16,7 +16,7 @@
 
 int event_notifier_init(EventNotifier *e, int active)
 {
-    e->event = CreateEvent(NULL, FALSE, FALSE, NULL);
+    e->event = CreateEvent(NULL, TRUE, FALSE, NULL);
     assert(e->event);
     return 0;
 }