bpo-38500: Add _PyInterpreterState_SetEvalFrameFunc() (GH-17340)

PyInterpreterState.eval_frame function now requires a tstate (Python
thread state) parameter.

Add private functions to the C API to get and set the frame
evaluation function:

* Add tstate parameter to _PyFrameEvalFunction function type.
* Add _PyInterpreterState_GetEvalFrameFunc() and
  _PyInterpreterState_SetEvalFrameFunc() functions.
* Add tstate parameter to _PyEval_EvalFrameDefault().
diff --git a/Include/cpython/ceval.h b/Include/cpython/ceval.h
index e601304..f03b53a 100644
--- a/Include/cpython/ceval.h
+++ b/Include/cpython/ceval.h
@@ -21,7 +21,7 @@
    flag was set, else return 0. */
 PyAPI_FUNC(int) PyEval_MergeCompilerFlags(PyCompilerFlags *cf);
 
-PyAPI_FUNC(PyObject *) _PyEval_EvalFrameDefault(struct _frame *f, int exc);
+PyAPI_FUNC(PyObject *) _PyEval_EvalFrameDefault(PyThreadState *tstate, struct _frame *f, int exc);
 
 PyAPI_FUNC(void) _PyEval_SetSwitchInterval(unsigned long microseconds);
 PyAPI_FUNC(unsigned long) _PyEval_GetSwitchInterval(void);