Add nested classes to parse tree dumped out by -xml

Previously the parse tree contained the forward class declaration for
nested classes, the <classforward> XML element as nested class
support had not been turned on during parsing for -xml. The nested
class support has now been turned on so that the nested classes appear
in the parse tree in a <class> XML element.

Closes #874

CHANGES.current

@@ -7,6 +7,9 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.3.0 (in progress)
 ===========================
 
+2024-10-16: wsfulton
+            #874 Add nested classes to the parse tree dumped out by -xml.
+
 2024-10-16: wsfulton
             #2213 Documentation for the XML output options of SWIG's parse tree has
             been added to the Extending chapter.

Source/Modules/xml.cxx

@@ -30,7 +30,7 @@ public:
   XML() :indent_level(0) , id(0) {
   }
   
-  virtual ~ XML() {
+  ~XML() {
   }
 
   virtual void main(int argc, char *argv[]) {
@@ -261,6 +261,9 @@ public:
     Printf(out, "</%s>\n", markup);
   }
 
+  NestedClassSupport nestedClassesSupport() const {
+    return NCS_Full;
+  }
 };
 
 /* -----------------------------------------------------------------------------