Clean up after bpo-33738. (GH-7627)

* Add declarations even if they are overridden by macros.
* Make the declaration and the definition of PyExceptionClass_Name
  consistent.
diff --git a/Include/pyerrors.h b/Include/pyerrors.h
index 5fd981c..5b62658 100644
--- a/Include/pyerrors.h
+++ b/Include/pyerrors.h
@@ -140,11 +140,10 @@
 #define PyExceptionInstance_Check(x)                    \
     PyType_FastSubclass((x)->ob_type, Py_TPFLAGS_BASE_EXC_SUBCLASS)
 
+PyAPI_FUNC(char *) PyExceptionClass_Name(PyObject *);
 #ifndef Py_LIMITED_API
 #define PyExceptionClass_Name(x) \
      ((char *)(((PyTypeObject *)(x))->tp_name))
-#else
-     PyAPI_FUNC(const char *) PyExceptionClass_Name(PyObject *);
 #endif
 
 #define PyExceptionInstance_Class(x) ((PyObject*)((x)->ob_type))