FB: Remove Q_FALLTHROUGH, which was introduced in Qt 5.8

... and we still depend on 5.7 here.

resources/facebook/eventslistjob.cpp

@@ -61,9 +61,8 @@ KCalCore::Incidence::Status EventsListJob::parseStatus(const QJsonObject &data)
     case Graph::NotResponded:
         return KCalCore::Incidence::StatusNeedsAction;
     case Graph::Declined:
-        Q_FALLTHROUGH();
     case Graph::Birthday:
-        Q_FALLTHROUGH();
+        break;
     }
 
     return KCalCore::Incidence::StatusNone;