Use wxUIntPtr instead of wxClientData in wxDataViewListCtrl.

Do not delete the client data in wxDataViewListCtrl, this class mainly exists
for compatibility with wxListCtrl and as the latter doesn't delete its client
data, neither should the former.

See #11088.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71561 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -505,6 +505,11 @@ Major new features in this release
 2.9.4:
 ------
 
+INCOMPATIBLE CHANGES SINCE 2.9.3
+
+- wxDataViewListCtrl doesn't delete its client data any more for compatibility
+  with wxListCtrl, use full wxDataViewCtrl if you don't need compatibility.
+
 All:
 
 - Added wxLogFormatter to allow customizing wxLog output (Sébastien Gallou).