Fix S4U2Self against non-FAST KDCs

When we added FAST TGS support in 1.11, we broke S4U2Self against KDCs
which don't support FAST, because the S4U2Self padata is only present
within the FAST request.  For now, duplicate that padata in the outer
request so that both FAST and non-FAST KDCs can see it.

(cherry picked from commit 55c3a5f69919c2b5435bac0cb48ab09b11be869c)

https://github.com/krb5/krb5/commit/7b461608791ba07049be66f6b599b1d1b81eb457
Author: Greg Hudson <ghudson@mit.edu>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 7b461608791ba07049be66f6b599b1d1b81eb457
Branch: krb5-1.11
 src/lib/krb5/krb/fast.c |   39 ++++++++++++++++++++++++++++++++++-----
 1 files changed, 34 insertions(+), 5 deletions(-)