krb5: new tag krb5-1.15-final

[Tom Yu]

A new lightweight tag "krb5-1.15-final" has been created in the krb5
repository for the following commit:

commit 3051931836c20208100b8f9d938145c6c5c702e8
Author: Tom Yu <tlyu at mit.edu>
Date:   Wed Nov 30 18:39:32 2016 -0500

    Updates for krb5-1.15