Add autogen _tags file, add special rule for invoking rpclib.idl at the bottom
Add autogen _tags file, add special rule for invoking rpclib.idl at the bottom

djs55/xcp-idl,xapi-project/message-switch,xapi-project/message-switch,xapi-project/message-switch,johnelse/xcp-idl,euanh/xcp-idl,Chunjie/xcp-idl