QWindowsFontDatabaseBase: Fix unused parameter error

Change-Id: Ifa2cc45c1bf4326a1273a713e3db950846d2ca14
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

src/gui/text/windows/qwindowsfontdatabasebase.cpp

@@ -575,6 +575,8 @@ bool QWindowsFontDatabaseBase::init(QSharedPointer<QWindowsFontEngineData> d)
             return false;
         }
     }
+#else
+    Q_UNUSED(d);
 #endif // directwrite && direct2d
     return true;
 }