_AddFunction
status_t _AddFunction(Function* function);
error = _AddFunction(subprogramEntry, unit, functions);
error = _AddFunction(static_cast<DIESubprogram*>(memberEntry),
error = _AddFunction(subprogramEntry, unit, functions);
status_t _AddFunction(DIESubprogram* subprogramEntry,
status_t error = _AddFunction(function);