aio / timers: Add QEMUTimerListGroup to AioContext

Add a QEMUTimerListGroup each AioContext (meaning a QEMUTimerList
associated with each clock is added) and delete it when the
AioContext is freed.

Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/async.c b/async.c
index 9791d8e..cd4a489 100644
--- a/async.c
+++ b/async.c
@@ -205,6 +205,7 @@
     event_notifier_cleanup(&ctx->notifier);
     qemu_mutex_destroy(&ctx->bh_lock);
     g_array_free(ctx->pollfds, TRUE);
+    timerlistgroup_deinit(&ctx->tlg);
 }
 
 static GSourceFuncs aio_source_funcs = {
@@ -244,6 +245,7 @@
     aio_set_event_notifier(ctx, &ctx->notifier, 
                            (EventNotifierHandler *)
                            event_notifier_test_and_clear);
+    timerlistgroup_init(&ctx->tlg);
 
     return ctx;
 }