Fix column sorting UI in wxDataViewCtrl under wxOSX.

Use -outlineView:didClickTableColumn: delegate method instead of
mouseDownInHeaderOfTableColumn: one to ensure that:

(a) We don't sort the column if it's being dragged/resized (closes #15340).
(b) We sort the column on mouse up, not down (closes #15386).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74635 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -575,6 +575,10 @@ wxMSW:
 
 - It is now possible to tab into radio boxes again.
 
+wxOSX:
+
+- Fix column sorting UI in wxDataViewCtrl (Myrsloik).
+
 
 2.9.5: (released 2013-07-15)
 ----------------------------