More RPC debugging tips without special configuration.

!rpcexts.thread & !rpcexts.obj - debug stuck rpc calls.
!rpcexts.stubmsg & !rpcexts.rpcmsg - stack based debugging.

I believe this is the only way to debug in Win2k since built-in rpc debug support is present only in XP or above. No time to blog all the details of using them, maybe later when I have more time.