Add a test to test that logging works in isolated child processes.
Only logSetFile is tested, because stdout and stderr are closed for
isolated child processes, and syslog and the none logging destinations
are expected to be the same as non-isolated processes.
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
