Use PyObject_GetDict instead of _PyObject_GetDictPtr

ZODB try to get object's dict and copy it without modification.
Pyston can't provide a writable dict. However, it can provide a
copy of object's dict. So add a new PyObject_GetDict API to return
a copy of object's dict. And let ZODB use this API.

src/persistent/cPersistence.c

@@ -171,13 +171,16 @@ ghostify(cPersistentObject *self)
     _estimated_size_in_bytes(self->estimated_size);
   ring_del(&self->ring);
   self->state = cPersistent_GHOST_STATE;
+  // Pyston change:
+  PyObject_ClearDict((PyObject *)self);
+#if 0
   dictptr = _PyObject_GetDictPtr((PyObject *)self);
   if (dictptr && *dictptr)
     {
       Py_DECREF(*dictptr);
       *dictptr = NULL;
     }
-
+#endif
   /* We remove the reference to the just ghosted object that the ring
    * holds.  Note that the dictionary of oids->objects has an uncounted
    * reference, so if the ring's reference was the only one, this frees
@@ -251,12 +254,15 @@ Per__p_deactivate(cPersistentObject *self)
 {
   if (self->state == cPersistent_UPTODATE_STATE && self->jar)
     {
+      PyObject_ClearDict(self);
+#if 0
       PyObject **dictptr = _PyObject_GetDictPtr((PyObject *)self);
       if (dictptr && *dictptr)
         {
           Py_DECREF(*dictptr);
           *dictptr = NULL;
         }
+#endif
       /* Note that we need to set to ghost state unless we are
          called directly. Methods that override this need to
          do the same! */
@@ -390,9 +396,19 @@ pickle___getstate__(PyObject *self)
   if (!slotnames)
     return NULL;
 
+  /** 
+   * Pyston change: Pyston didn't support _PyObject_GetDictPtr fully
+   * And will not support it in future
+   */
+#if 0
   dictp = _PyObject_GetDictPtr(self);
   if (dictp)
     state = pickle_copy_dict(*dictp);
+#endif
+
+  PyObject *dict = PyObject_GetDict(self);
+  if (dict)
+    state = pickle_copy_dict(dict);
   else
     {
       state = Py_None;
@@ -502,6 +518,7 @@ pickle___setstate__(PyObject *self, PyObject *state)
     {
       PyObject **dict;
 
+#if 0
       dict = _PyObject_GetDictPtr(self);
       
       if (!dict)
@@ -521,6 +538,9 @@ pickle___setstate__(PyObject *self, PyObject *state)
       PyDict_Clear(*dict);
       if (PyDict_Update(*dict, state) < 0)
         return NULL;
+#endif
+      PyObject_ClearDict((PyObject*)self);
+      PyObject_SetDict(self, state);
     }
 
   if (slots && pickle_setattrs_from_dict(self, slots) < 0)