main-loop: Suppress "I/O thread spun" warnings for qtest

When running under qtest we don't actually have any vcpu threads
to be starved, so the warning about the I/O thread spinning isn't
relevant, and the way qtest manipulates the simulated clock means
the warning is produced a lot as a false positive. Suppress it if
qtest_enabled(), so 'make check' output is less noisy.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
diff --git a/stubs/qtest.c b/stubs/qtest.c
new file mode 100644
index 0000000..e671ed8
--- /dev/null
+++ b/stubs/qtest.c
@@ -0,0 +1,14 @@
+/*
+ * qtest stubs
+ *
+ * Copyright (c) 2014 Linaro Limited
+ * Written by Peter Maydell
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu-common.h"
+
+/* Needed for qtest_allowed() */
+bool qtest_allowed;