MDL-22887 - changing variable $courseid to $calendar->courseid;

calendar/renderer.php

@@ -612,7 +612,7 @@ public function show_upcoming_events(calendar_information $calendar, $futuredays
                 // Convert to calendar_event object so that we transform description
                 // accordingly
                 $event = new calendar_event($event);
-                $event->calendarcourseid = $courseid;
+                $event->calendarcourseid = $calendar->courseid;
                 $output .= $this->event($event);
             }
             $output .= html_writer::end_tag('div');