[krbdev.mit.edu #2641] KRB5_KDB_DISALLOW_SVR flag unnecessarily prevents User2User

[Sam Hartman via RT]

I'm a bit concerned because I believe that allow dup skey is the
default.  I'm not sure that the behavior people expect when they turn
off allow_svr is to enable user2user.

I'd be interested in other comments on this.