consistently use Py_TYPE, Py_REFCNT, and correct initializer macros (#3563)

This no-op change makes 2.7 more consistent with 3.x to ease comparison and backports.
diff --git a/Modules/_sqlite/connection.c b/Modules/_sqlite/connection.c
index 237d6e4..439542e 100644
--- a/Modules/_sqlite/connection.c
+++ b/Modules/_sqlite/connection.c
@@ -293,7 +293,7 @@
     Py_XDECREF(self->statements);
     Py_XDECREF(self->cursors);
 
-    self->ob_type->tp_free((PyObject*)self);
+    Py_TYPE(self)->tp_free((PyObject*)self);
 }
 
 /*