Fix E_RECOVERABLE_ERROR in event_api

Argument 3 passed to event_type_execute() must be of the type array,
integer given, called in /home/dregad/dev/mantisbt/core/event_api.php on
line 153 and defined

Regression introduced by 5458f7020999317b35f403fa2a0e477d6182ec12.
Follow up fix on af6c6e559b9b92d83c93fb5e6633e9c249da1f77.