Include authenticator and ticket authdata in gss-api

Include authenticator and ticket authdata in gss-api

Currently, the GSS-API routines for handling authdata only extract the
authorization data from the ticket, not that from the authenticator.
This is incorrect.  Introduce a new function krb5_merge_authadata to
merge two authdata arrays into a newly allocated result array.  Use
this function in accept_sec_context.c to include both sets of
authdata.

ticket: 6400
Target_version: 1.7
Tags: pullup

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@22056 dc483132-0cff-0310-8789-dd5450dbe970