Virtualize wxXmlNode methods used by wxAuiToolBarXmlHandler.

This fixes the DLL build of aui library as it can now be linked without
leaving any unresolved dependencies to the code in xml library (where
wxXmlNode is implemented).

Closes #15686.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75734 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/xrc/xmlres.h

@@ -651,11 +651,50 @@ protected:
     */
     wxString GetName();
 
+    /**
+        Checks if the given node is an object node.
+
+        Object nodes are those named "object" or "object_ref".
+
+        @since 3.1.0
+    */
+    bool IsObjectNode(const wxXmlNode *node) const;
     /**
         Gets node content from wxXML_ENTITY_NODE.
     */
     wxString GetNodeContent(wxXmlNode* node);
 
+    /**
+        Gets the parent of the node given.
+
+        This method is safe to call with @NULL argument, it just returns @NULL
+        in this case.
+
+        @since 3.1.0
+    */
+    wxXmlNode *GetNodeParent(const wxXmlNode *node) const;
+
+    /**
+        Gets the next sibling node related to the given node, possibly @NULL.
+
+        This method is safe to call with @NULL argument, it just returns @NULL
+        in this case.
+
+        @since 3.1.0
+    */
+    wxXmlNode *GetNodeNext(const wxXmlNode *node) const;
+
+    /**
+        Gets the first child of the given node or @NULL.
+
+        This method is safe to call with @NULL argument, it just returns @NULL
+        in this case.
+
+        @since 3.1.0
+    */
+    wxXmlNode *GetNodeChildren(const wxXmlNode *node) const;
+
+
     /**
         Finds the node or returns @NULL.
     */