qemu-iotests: Adjust test result 039

The moved OFLAG_COPIED check in qcow2_check_refcounts results in a
different output from test 039 (mismatches are now found after the
general refcount check (as far as any remain)). This patch adjusts the
expected test result accordingly.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
