``Python.h`` no longer includes the ``<ctype.h>`` standard header file. If
needed, it should now be included explicitly. For example, it provides
``isalpha()`` and ``tolower()`` functions which are locale dependent. Python
provides locale independent functions, like :c:func:`!Py_ISALPHA` and
:c:func:`!Py_TOLOWER`. Patch by Victor Stinner.