Clean header files of interfaces defined but with no implementation. The
public API symbols being removed are:
``_PyBytes_InsertThousandsGroupingLocale``,
``_PyBytes_InsertThousandsGrouping``, ``_Py_InitializeFromArgs``,
``_Py_InitializeFromWideArgs``, ``_PyFloat_Repr``, ``_PyFloat_Digits``,
``_PyFloat_DigitsInit``, ``PyFrame_ExtendStack``, ``_PyAIterWrapper_Type``,
``PyNullImporter_Type``, ``PyCmpWrapper_Type``, ``PySortWrapper_Type``,
``PyNoArgsFunction``.
