* kdc_util.h: Added new prototypes for return_padata() and check_padata()

* kdc_util.h: Added new prototypes for return_padata() and check_padata()

* kdc_preauth.c (return_padata): New function which calls out to each preauth
	 type to see if it is necessary to return preauth data or not.
(return_pw_salt): New function responsible for returning the
	KRB5_PW_SALT preauth information.

* do_as_req.c (process_as_req):  Move creation of the PW_SALT
	preauthentication step into kdc_preauth.c.  Call return_pdata()
	which is responsible for all padata info which is returned by
	the KDC in the KRB_AS_REP message.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@7103 dc483132-0cff-0310-8789-dd5450dbe970