Fix race between queueing the pdu and update the task data

After we have called iscsi_queue_pdu from iscsi_scsi_command_async
the pdu might have already completed if we are using multithreading
so we should not dereference pdu at that point.

Move the assignment of task->cmdsn and task->itt we need for
task management into iscsi_pdu_set_cmdsn instead.

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>

lib/socket.c

@@ -149,7 +149,7 @@ iscsi_add_to_outqueue(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
 
  finished:
         iscsi_mt_spin_unlock(&iscsi->iscsi_lock);
-
+        
         /* TODO QQQ need to immediately send for the non multithreading case too
          * and for the Windows API too */
 #if defined(HAVE_MULTITHREADING) && defined(HAVE_PTHREAD)