bpo-36974: rename _FastCallKeywords -> _Vectorcall (GH-13653)

diff --git a/Objects/call.c b/Objects/call.c
index 55dfc52..acd1f26 100644
--- a/Objects/call.c
+++ b/Objects/call.c
@@ -374,8 +374,8 @@
 
 
 PyObject *
-_PyFunction_FastCallKeywords(PyObject *func, PyObject* const* stack,
-                             size_t nargsf, PyObject *kwnames)
+_PyFunction_Vectorcall(PyObject *func, PyObject* const* stack,
+                       size_t nargsf, PyObject *kwnames)
 {
     PyCodeObject *co = (PyCodeObject *)PyFunction_GET_CODE(func);
     PyObject *globals = PyFunction_GET_GLOBALS(func);
@@ -714,9 +714,9 @@
 
 
 PyObject *
-_PyCFunction_FastCallKeywords(PyObject *func,
-                              PyObject *const *args, size_t nargsf,
-                              PyObject *kwnames)
+_PyCFunction_Vectorcall(PyObject *func,
+                        PyObject *const *args, size_t nargsf,
+                        PyObject *kwnames)
 {
     PyObject *result;