'event' must be non NULL, remove test.

'event' must be non NULL, remove test.

1401        }

	CID 1453455 (#1 of 1): Dereference before null check (REVERSE_INULL)
	check_after_deref: Null-checking event suggests that it may be null,
	but it has already been dereferenced on all paths leading to the check.

1402        if (event != NULL)
1403                isc_event_free(ISC_EVENT_PTR(&event));