In the limited C API, ``PyObject_INIT()`` and ``PyObject_INIT_VAR()`` are
now defined as aliases to :c:func:`PyObject_Init` and
:c:func:`PyObject_InitVar` to make their implementation opaque. It avoids to
leak implementation details in the limited C API. Exclude the following
functions from the limited C API: ``_Py_NewReference()``,
``_Py_ForgetReference()``, ``_PyTraceMalloc_NewReference()`` and
``_Py_GetRefTotal()``.
