Fix definition of move assignment operator for wrapper classes

Classes not deriving from another class in the hierarchy must take care
of freeing their current pointer before reassigning it.

This should have been part of 3f3438093 (Define move ctor and assignment
operator for C++ wrappers, 2021-11-24).

Source/Modules/c.cxx

@@ -372,6 +372,7 @@ public:
     );
 
     class_node_ = n;
+    dtor_wname_ = NULL;
     has_copy_ctor_ = false;
   }
 
@@ -569,6 +570,9 @@ public:
 	  cindent, "}\n",
 	  NIL
 	);
+
+	// We're also going to need this in move assignment operator.
+	dtor_wname_ = wname;
       }
     } else if (is_member) {
       // Wrapper parameters list may or not include "this" pointer and may or not have other parameters, so construct it piecewise for simplicity.
@@ -703,11 +707,24 @@ public:
 	"swig_self_{obj.swig_self_}, swig_owns_self_{obj.swig_owns_self_} { "
 	"obj.swig_owns_self_ = false; "
 	"}\n",
-	cindent, classname, "& operator=(", classname, "&& obj) noexcept { "
-	"swig_self_ = obj.swig_self_; swig_owns_self_ = obj.swig_owns_self_; "
-	"obj.swig_owns_self_ = false; "
-	"return *this; "
-	"}\n",
+	cindent, classname, "& operator=(", classname, "&& obj) noexcept {\n",
+	NIL
+      );
+
+      if (dtor_wname_) {
+	Printv(cxx_wrappers_.sect_decls,
+	  cindent, cindent, "if (swig_owns_self_)\n",
+	  cindent, cindent, cindent, dtor_wname_, "(swig_self_);\n",
+	  NIL
+	);
+      }
+
+      Printv(cxx_wrappers_.sect_decls,
+	cindent, cindent, "swig_self_ = obj.swig_self_;\n",
+	cindent, cindent, "swig_owns_self_ = obj.swig_owns_self_;\n",
+	cindent, cindent, "obj.swig_owns_self_ = false;\n",
+	cindent, cindent, "return *this;\n",
+	cindent, "}\n",
 	NIL
       );
     }
@@ -1091,6 +1108,9 @@ private:
   type_desc* ptype_desc_;
   type_desc* rtype_desc_;
 
+  // Name of the C function used for deleting the owned object, if any.
+  String* dtor_wname_;
+
   // True if the class defines an explicit copy ctor.
   bool has_copy_ctor_;