Remove duplicate entry for PyObject_AsFileDescriptor. (Really, this time.)

Doc/c-api/abstract.rst

@@ -325,14 +325,6 @@ is considered sufficient for this determination.
    equivalent of the Python statement ``del o[key]``.
 
 
-.. cfunction:: int PyObject_AsFileDescriptor(PyObject *o)
-
-   Derives a file descriptor from a Python object.  If the object is an integer or
-   long integer, its value is returned.  If not, the object's :meth:`fileno` method
-   is called if it exists; the method must return an integer or long integer, which
-   is returned as the file descriptor value.  Returns ``-1`` on failure.
-
-
 .. cfunction:: PyObject* PyObject_Dir(PyObject *o)
 
    This is equivalent to the Python expression ``dir(o)``, returning a (possibly