Land from b_hd_pid to HEAD

b=bug4165(pid)
r=Peter

- Assign the constant number to kernel portals pid,
  this constant is LUSTRE_SRV_PTL_PID(999999) defined
  in lustre_idl.h;
  In the user mode(liblustre), use the getpid()

- Modify the struct ptlrpc_peer's field peer_nid
  from ptl_nid_t to ptl_process_id_t, which include pid.
  Modify the related code with peer_nid.

- Change the snprintf remote_uuid.uuid to
  include pid info in target_handle_connect;

- In ksocknal_api_startup, use LUSTRE_SRV_PTL_PID to PtlNIInit.

- In tcpnal_init, b->lib_nal->libnal_ni.ni_pid.pid=0;
  This line should be deleted.

- In ptlrpc_get_connection, add the pid compare
  when iterate the conn_list & conn_unused_list

- Change request_in_callback while assign req->rq_peer.peer_id

- In ptlrpc_uuid_to_peer, give default value
  (LUSTRE_SRV_PTL_PID) to peer->peer_id.pid

- Change each entry to call PtlNIInit/PtlPut

- Change the entry to call PtlMEAttach,
  use c_peer value replace PTL_PID_ANY , it is the most important!