bpo-36710: Add tstate parameter in ceval.c (GH-13547)

* Fix a possible reference leak in _PyErr_Print() if exception
  is NULL.
* PyErr_BadInternalCall(): replace PyErr_Format() with _PyErr_SetString().
* Add pycore_pyerrors.h header file.
* New functions:

  * _PyErr_Clear()
  * _PyErr_Fetch()
  * _PyErr_Print()
  * _PyErr_Restore()
  * _PyErr_SetObject()
  * _PyErr_SetString()

* Add 'tstate' parameter to _PyEval_AddPendingCall().

Include/internal/pycore_pyerrors.h

@@ -0,0 +1,62 @@
+#ifndef Py_INTERNAL_PYERRORS_H
+#define Py_INTERNAL_PYERRORS_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef Py_BUILD_CORE
+#  error "this header requires Py_BUILD_CORE define"
+#endif
+
+static inline PyObject* _PyErr_Occurred(PyThreadState *tstate)
+{
+    return tstate == NULL ? NULL : tstate->curexc_type;
+}
+
+
+PyAPI_FUNC(void) _PyErr_Fetch(
+    PyThreadState *tstate,
+    PyObject **type,
+    PyObject **value,
+    PyObject **traceback);
+
+PyAPI_FUNC(int) _PyErr_ExceptionMatches(
+    PyThreadState *tstate,
+    PyObject *exc);
+
+PyAPI_FUNC(void) _PyErr_Restore(
+    PyThreadState *tstate,
+    PyObject *type,
+    PyObject *value,
+    PyObject *traceback);
+
+PyAPI_FUNC(void) _PyErr_SetObject(
+    PyThreadState *tstate,
+    PyObject *type,
+    PyObject *value);
+
+PyAPI_FUNC(void) _PyErr_Clear(PyThreadState *tstate);
+
+PyAPI_FUNC(void) _PyErr_SetNone(PyThreadState *tstate, PyObject *exception);
+
+PyAPI_FUNC(void) _PyErr_SetString(
+    PyThreadState *tstate,
+    PyObject *exception,
+    const char *string);
+
+PyAPI_FUNC(PyObject *) _PyErr_Format(
+    PyThreadState *tstate,
+    PyObject *exception,
+    const char *format,
+    ...);
+
+PyAPI_FUNC(void) _PyErr_NormalizeException(
+    PyThreadState *tstate,
+    PyObject **exc,
+    PyObject **val,
+    PyObject **tb);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_INTERNAL_PYERRORS_H */