qemu-iotests: 067: ignore QMP events

qemu-iotests: 067: ignore QMP events

The relative ordering of "device_del" return value and the
"DEVICE_DELETED" QMP event depends on the architecture being
tested. On x86 unplugging virtio disks is asynchronous
(=qdev_unplug()= → =hotplug_handler_unplug_request()=) while on s390x
it is synchronous (=qdev_unplug()= → =hotplug_handler_unplug()=). This
leads to the actual output on s390x consistently differing from the
reference output (that was probably produced on x86).

The easiest way to address this is to filter out QMP events in
067. The DEVICE_DELETED event is already getting explicitly tested by
the Python-based test case 139, so the test coverage should be
unaffected. Make use of the recently introduced _filter_qmp_events()
to remove QMP events from the test case output and adjust the
reference output accordingly.

The tr / sed / tr trick used for filtering was suggested by Max Reitz
<mreitz@redhat.com>.

Signed-off-by: Sascha Silbe <silbe@linux.vnet.ibm.com>
Message-id: 1455886869-139916-2-git-send-email-silbe@linux.vnet.ibm.com
Signed-off-by: Max Reitz <mreitz@redhat.com>