Use correct name-type in TGS-REQs for 2008R2 RODCs

Correctly set the name-type for the TGS principals to KRB5_NT_SRV_INST
in TGS-REQs.  (Previously, only AS-REQs had the name-type set in this
way.)  Windows Server 2008 R2 read-only domain controllers (RODCs)
insist on having the correct name-type for the TGS principal in
TGS-REQs as well as AS-REQs, at least for the TGT-forwarding case.

Thanks to Sebastian Galiano for reporting this bug and helping with
testing.

https://github.com/krb5/krb5/commit/726d532f360b446cb4c2728a025ad1d5e68d41f7
Commit By: tlyu
Revision: 25839
Changed Files:
U   trunk/src/lib/krb5/krb/fwd_tgt.c
U   trunk/src/lib/krb5/krb/tgtname.c