Debugger: Code cosmetics

Sprinkling in const and ranged for.

Change-Id: I5d11d57f64140021397c23734c7373544ebebb6f
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/debugger/moduleshandler.h

@@ -129,7 +129,7 @@ public:
     void endUpdateAll();
 
     void removeAll();
-    Modules modules() const;
+    const Modules modules() const;
 
 private:
     ModuleItem *moduleFromPath(const QString &modulePath) const;