Use preauth options when changing password

If we try to change the password in rb5_get_init_creds_password, we
must use all application-specified gic options which affect
preauthentication when getting the kadmin/changepw ticket.  Create a
helper function make_chpw_options which copies the application's
options, unsets the options we don't want, and sets options
appropriate for a temporary ticket.

https://github.com/krb5/krb5/commit/9f9c4acd9629913d2ff197e0f4994d091f2073d5
Author: Greg Hudson <ghudson@mit.edu>
Commit: 9f9c4acd9629913d2ff197e0f4994d091f2073d5
Branch: master
 src/lib/krb5/krb/gic_pwd.c |   63 +++++++++++++++++++++++++++++++++++--------
 1 files changed, 51 insertions(+), 12 deletions(-)