Removed unused XPT_ALLOC macro.
Move XPT_SetDataOffset calls into XPT_DoHeader so that the API consumer doesn't
need to know about header sizing and IDE layout guck.
Handle NULL namespaces and interface_directory bits snd idents better.
Made xpt_dump show the the IID for interfaces.
git-svn-id: svn://10.0.0.236/trunk@19992 18797224-902f-48f8-a5cc-f745e15eee43