/usr/include/kadm5/kadm_err.h is in libkrb5-dev 1.13.2+dfsg-5ubuntu2.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/include/kadm5/../mit-krb5/kadm5/kadm_err.h
/usr/include/kadm5/../mit-krb5/kadm5/kadm_err.h