Remove support for setting a client flag indicating pkinit is used on the db entry.

Remove support for setting a client flag indicating pkinit is used on the db entry.
I'm reasonably sure that this would belong in a pkinit plugin not in do_as_req.c.
Also, the flag should be documented to indicate what it means--client attempted pkinit?  Client succeeded in using pkinit?
I also wonder  whether you want a mechanism for a db plugin to figure out  all the padata or fast factors that a request is using.
Note that  this flag will need to be added back by at least one vendor.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@21694 dc483132-0cff-0310-8789-dd5450dbe970