[krbdev.mit.edu #6893] error codes from error responses can be discarded when there's e-data

[Greg Hudson via RT]

I think the correct way to handle an unframed KRB-ERROR response 
containing e_data is to handle it as if it were a framed KRB-ERROR 
response.  Currently, that means ignoring the error code and instead 
returning success with the numeric result code in the e_data.

Unfortunately, the way the code is currently structured, it would be a 
little tricky to bypass the vno/ap_rep.length logic to get to the code for 
handling a framed KRB-ERROR, so this will require some restructuring.