Attribute of SWIG wrapped classes instances were overwritten on __init__()

When a SWIG classes instances is initialized, its internal dictionary was
reset to NULL, which result in the loss of any attribute that might have
been set for the instance.

Only initialize the internal dictionary on actual PyObject creation.

class Test(MySwigWrappedClass):
        def __init__(self):
                self.val = "Random Value"
                MySwigWrappedClass.__init__(self)

p = Test()
print hasattr(p, "val") # Should return True, but used to return False

Lib/python/pyrun.swg

@@ -1437,18 +1437,21 @@ SWIG_Python_NewPointerObj(PyObject *self, void *ptr, swig_type_info *type, int f
 	  newobj = (SwigPyObject *) newobj->next;
         newobj->next = next_self;
         newobj = (SwigPyObject *)next_self;
+#ifdef SWIGPYTHON_BUILTIN
+        newobj->dict = 0;
+#endif
       }
     } else {
       newobj = PyObject_New(SwigPyObject, clientdata->pytype);
+#ifdef SWIGPYTHON_BUILTIN
+      newobj->dict = 0;
+#endif
     }
     if (newobj) {
       newobj->ptr = ptr;
       newobj->ty = type;
       newobj->own = own;
       newobj->next = 0;
-#ifdef SWIGPYTHON_BUILTIN
-      newobj->dict = 0;
-#endif
       return (PyObject*) newobj;
     }
     return SWIG_Py_Void();