[krbdev.mit.edu #8607] kpropd should write a pidfile when started in standalone mode...

[john@iastate.edu via RT]

...so it can be properly managed by systemctl etc.

I have included a sample patch to implement this.
NOTE: I changed the command line flags to match the other kerberos daemons
<https://imgflip.com/i/1uj6yv>:

# ./kpropd -h
Usage: ./kpropd [-r realm] [-s srvtab] [-dS] [-f slave_file]
 [-F kerberos_db_file ] [-u kdb5_util_pathname]
 [-x db_args]* [-p port] [-a acl_file]
 [-P pid_file] (standalone mode only)
 [-A admin_server]

John