This is a cleanup of the sigio/sigurg code.

Summary:
  o Removed sk->proc, SIGURG now sent via vfs, credentials checked
    during delivery.
  o SIOCSPGRP etc. ioctls use vfs, and work now for SIGIO as well
    as SIGURG.
  o Removed socket fcntl code.
  o Consolidate lsm file_set_fowner() hooks.
  o Fixed fowner race.
  o Fixed associated mainline memory leak in fcntl_dirnotify().