rc.d/kdc: Support start of MIT krb5kdc

[cy]

Summary

Some users wishing to use the MIT krb5kdc have discovered the
kdc script workaround applied to the MIT krb5 ports is insufficient.
Let's build into this rc script the smarts to determine whether
base or ports Hiemdal kdc is being invoked or the MIT krb5kdc.

Suggested by: netchild
Original patch: netchild
MFC after: 1 week

Test Plan

Will run it here for a few days.

[emaste]

Looks reasonable to me, line is longer than 80 cols though

[cy]

Reduce line length.

[netchild]

libexec/rc/rc.d/kdc

19–25

You can get rid of the kdc_start_precmd() completely. You want to make sure kdc_program is set (all config files loaded), so I would move the check to after load_rc_config. This would also make my patch in progress for service jails more easy, as it needs to get rid of the precmd anyway to work for the kdc.

Additionally to my suggested edit, you need to remove the "start_precmd=${name}_start_precmd" line.

[cy]

Prepare for service jail patch.