In KDC, log client principal in bad header ticket

Fix KDC logging to include client principal in TGS_REQ logging even
during error conditions such as "Ticket expired".  As long as the
TGS_REQ can be decrypted and the client principal is available, it
should be included in the log, regardless of other errors which might
be detected.

krb5_rd_req_decoded and krb5_rd_req_decoded_anyflag (not public
interfaces) now leave the decrypted ticket in req->ticket->enc_part2
on success or failure, if the ticket was successfully decrypted.  This
does not affect the behavior of krb5_rd_req.

[ghudson@mit.edu: removed extraneous change, added commit message
summary and description of internal API change, fixed possible memory
leak, removed comment and #if 0 code block of purely historical
interest]

ticket: 7910
Add test for KDC client logging

Add a test case which performed a TGS request with an expired ticket
and checks that the client principal is logged.

ticket: 7910
Simplify ticket retrieval from AP-REQs

After krb5_rd_req_decoded or krb5_rd_req_decoded_anyflag, the ticket
(with enc_part2 if we could decrypt it) is accessible via
request->ticket; there is no need to copy it.  Stop using the ticket
parameter of those functions.  Where we need to save the ticket beyond
the lifetime of the krb5_ap_req, steal the pointer before freeing the
request.
Add missing profile functions to libkrb5 exports

profile_flush_to_buffer, profile_flush_to_file, profile_free_buffer,
profile_init_flags, and profile_init_vtable are all public profile
functions, but are inaccessible to libkrb5 applications on some
platforms because they were never added to the export list.  Add them
now.

(libprofile functions have never been part of the Windows DLL export
list, so do not change krb5_32.def at this time.)

ticket: 7930 (new)
target_version: 1.12.2
tags: pullup
Remove stub pkinit_win2k code

As contributed, the PKINIT module contained code to read the
pkinit_win2k variable, but never used it.  Get rid of the structure
field and the code to populate it.
Do not document pkinit_win2k

This variable was never used in the PKINIT code as it was contributed;
there was only code to read its value.

ticket: 7932 (new)
target_version: 1.12.2
tags: pullup