Handle TGS referrals to the same realm

Handle TGS referrals to the same realm

krb5 1.6 through 1.8 contained a workaround for the Active Directory
behavior of returning a TGS referral to the same realm as the request.
1.9 responds to this behavior by caching the returned TGT, trying
again, and detecting a referral loop.  This is a partial regression of
ticket #4955.  Detect this case and fall back to a non-referreal
request.

ticket: 7016
target_version: 1.9.3
tags: pullup

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@25472 dc483132-0cff-0310-8789-dd5450dbe970