Revert "Backport METH_FASTCALL from Python 3.7 (#328)"

This reverts commit cf73bbd678.

third_party/python/Include/methodobject.h

@@ -14,12 +14,10 @@ extern PyTypeObject PyCFunction_Type;
 #define PyCFunction_Check(op) (Py_TYPE(op) == &PyCFunction_Type)
 
 typedef PyObject *(*PyCFunction)(PyObject *, PyObject *);
-typedef PyObject *(*_PyCFunctionFast) (PyObject *, PyObject **, Py_ssize_t);
+typedef PyObject *(*_PyCFunctionFast) (PyObject *self, PyObject **args,
+                                       Py_ssize_t nargs, PyObject *kwnames);
 typedef PyObject *(*PyCFunctionWithKeywords)(PyObject *, PyObject *,
                                              PyObject *);
-typedef PyObject *(*_PyCFunctionFastWithKeywords) (PyObject *,
-                                                   PyObject **, Py_ssize_t,
-                                                   PyObject *);
 typedef PyObject *(*PyNoArgsFunction)(PyObject *);
 
 PyCFunction PyCFunction_GetFunction(PyObject *);
@@ -95,20 +93,12 @@ typedef struct {
     PyObject    *m_module; /* The __module__ attribute, can be anything */
     PyObject    *m_weakreflist; /* List of weak references */
 } PyCFunctionObject;
-
 PyObject * _PyMethodDef_RawFastCallDict(
     PyMethodDef *method,
     PyObject *self,
     PyObject **args,
     Py_ssize_t nargs,
     PyObject *kwargs);
-
-PyObject * _PyMethodDef_RawFastCallKeywords(
-    PyMethodDef *method,
-    PyObject *self,
-    PyObject **args,
-    Py_ssize_t nargs,
-    PyObject *kwnames);
 #endif
 
 int PyCFunction_ClearFreeList(void);