remove unused XMLBase

tinyxml2.h

@@ -893,7 +893,6 @@ private:
 */
 class TINYXML2_LIB XMLText : public XMLNode
 {
-    friend class XMLBase;
     friend class XMLDocument;
 public:
     virtual bool Accept( XMLVisitor* visitor ) const;
@@ -1142,7 +1141,6 @@ private:
 */
 class TINYXML2_LIB XMLElement : public XMLNode
 {
-    friend class XMLBase;
     friend class XMLDocument;
 public:
     /// Get the name of an element (which is the Value() of the node.)