We can't rely on having every KDC support FAST and should still
support S4U2Self against such a KDC.
We also have the order of the PA-DATA elements "corrected",
KRB5_PADATA_TGS_REQ followed by KRB5_PADATA_FX_FAST and
finally KRB5_PADATA_FOR_USER. While the inner PA-DATA
only contains KRB5_PADATA_FOR_USER.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=15002
Signed-off-by: Stefan Metzmacher <metze@samba.org>