Its useful to get a CSV output on stdout for test frameworks to read
and parse the results. However, a csv file is not always needed.
Add the -z option to create/append a csv file only when the user
asks for it.
Signed-off-by: Axel Haslam <ahaslam@baylibre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>