Modify internal TclStubInfoType type:  use TclStubs * in stead of ClientData, so less type casts are needed in the code. 
Disadvantage: somewhat more code duplication, but it makes the code much more understandable.
Don't use TclpInetNtoa any more, use inet_ntoa in stead. Since IP6 support it's even not necessary any more (except for fake-rfc2553, but mutexes are used here already) , but it's in the internal stub table so we cannot remove it unto 9.0