Using 'default_order', 'default_is_section', 'default_weight' in 'order_bys' and the need for 'default' => '1'

Two of the supplied reports (Activity.php and Event/ParticipantListing.php) specify 'default_weight' in multiple 'order_bys' arrays, but don't specify 'default' => '1' so those 'order_bys' are not processed.

There are two ways to fix this:

(1) Form.php.diff provides an enhancement where if 'default_order', 'default_is_section', or 'default_weight' is specified, then 'default' => '1' is implied.

(2) Activity.php.diff and ParticipantListing.php.diff update the 'order_bys' to include 'default' => '1'.

Patch CRM-9838 is required for either of these options to work.