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/_testcapimodule.c b/Modules/_testcapimodule.c
index ecc473c..7691b51 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -187,8 +187,7 @@
  *   PyType_Ready if it hasn't already been called
  */
 static PyTypeObject _HashInheritanceTester_Type = {
-    PyObject_HEAD_INIT(NULL)
-    0,                          /* Number of items for varobject */
+    PyVarObject_HEAD_INIT(NULL, 0)
     "hashinheritancetester",            /* Name of this type */
     sizeof(PyObject),           /* Basic object size */
     0,                          /* Item size for varobject */
@@ -315,8 +314,7 @@
 };
 
 static PyTypeObject _MemoryViewTester_Type = {
-    PyObject_HEAD_INIT(NULL)
-    0,                          /* Number of items for varobject */
+    PyVarObject_HEAD_INIT(NULL, 0)
     "memoryviewtester",         /* Name of this type */
     sizeof(PyObject),           /* Basic object size */
     0,                          /* Item size for varobject */