Correct implement wxLIST_AUTOSIZE_XXX in the generic wxListCtrl.

Use both the contents and the header width when wxLIST_AUTOSIZE_USEHEADER is
given instead of just the latter.

Also make both wxLIST_AUTOSIZE_USEHEADER and the previously implemented
wxLIST_AUTOSIZE work efficiently for the virtual list controls by reusing
wxMaxWidthCalculatorBase already used in the generic wxDataViewCtrl.

Closes #10326.

include/wx/generic/private/listctrl.h

@@ -863,6 +863,7 @@ private:
     DECLARE_EVENT_TABLE()
 
     friend class wxGenericListCtrl;
+    friend class wxListCtrlMaxWidthCalculator;
 };
 
 #endif // wxUSE_LISTCTRL