also hide arc label line when gauge_label_show is false

src/arc.js

@@ -306,7 +306,7 @@ c3_chart_internal_fn.redrawArc = function (duration, durationForExit, withTransf
         else {
             mainArcLabelLine
                 .style("fill", function (d) { return config.color_pattern.length > 0 ? $$.levelColor(d.data.values[0].value) : $$.color(d.data); })
-                .style("display", "")
+                .style("display", config.gauge_label_show ? "" : "none")
                 .each(function (d) {
                     var lineLength = 0, lineThickness = 2, x = 0, y = 0, transform = "";
                     if ($$.hiddenTargetIds.indexOf(d.data.id) < 0) {