r4729: add dummy "winbind" service

r4729: add dummy "winbind" service

- this creates a new task and then starts a process_model "single"
  with service "winbind_task"

- that means with -M single everything is in one process

  with - M standard winbind is a seperate process but didn't fork for each connection
  with -M thread winbind is a seperate thread but didn't thread for each connection

- the dummy server listen s on /tmp/.winbind/echo
  and for better testing with telnet also on 127.0.255.1 port 55555

metze
(This used to be commit 5190f60dedc4076d94fbf77e02eb3b5312d953ec)