fixes to multi map iterator for removal, in older qt

src/base/circularplot/qucircularplotengine.cpp

@@ -518,7 +518,11 @@ float QuCircularPlotEngine::curveSelectedPointRadius()  const {
  *
  */
 void QuCircularPlotEngine::addDrawable(QuCircularPlotDrawable_I *dra) {
+#if QT_VERSION >= QT_VERSION_CHECK(5,15,0)
+    d.drawables.insert(dra->z(), dra);
+#else
     d.drawables.insertMulti(dra->z(), dra);
+#endif
 }
 
 /*!
@@ -526,7 +530,11 @@ void QuCircularPlotEngine::addDrawable(QuCircularPlotDrawable_I *dra) {
  * \param dra QuCircularPlotDrawable_I to remove (without deletion)
  */
 void QuCircularPlotEngine::removeDrawable(QuCircularPlotDrawable_I *dra) {
+#if QT_VERSION >= QT_VERSION_CHECK(5,15,0)
     QMutableMultiMapIterator<int, QuCircularPlotDrawable_I *> mmi(d.drawables);
+#else
+    QMultiMapIterator<int, QuCircularPlotDrawable_I *> mmi(d.drawables);
+#endif
     while(mmi.hasNext()) {
         mmi.next();
         if(mmi.value() == dra)