fix -Woverloaded-virtual

src/Mod/TechDraw/App/DrawLeaderLine.cpp

@@ -155,7 +155,7 @@ bool DrawLeaderLine::keepUpdated(void)
     return result;
 }
 
-double DrawLeaderLine::getScale(void)
+double DrawLeaderLine::getScale(void) const
 {
     double result = 1.0;
     DrawView* parent = getBaseView();

src/Mod/TechDraw/App/DrawLeaderLine.h

@@ -64,7 +64,7 @@ public:
     DrawView* getBaseView(void) const;
     virtual App::DocumentObject* getBaseObject(void) const;
     bool keepUpdated(void);
-    double getScale(void);
+    double getScale(void) const;
     void adjustLastSegment(void);
     bool getDefAuto(void) const;