OS-7088 cyclics corked on overlay socket with full queue

*** 1105,1115 ****
  
  out:
          mutex_enter(&odd->odd_lock);
          overlay_io_done(odd, OVERLAY_F_IN_TX);
          mutex_exit(&odd->odd_lock);
!         return (mp_chain);
  }
  
  /* ARGSUSED */
  static void
  overlay_m_ioctl(void *arg, queue_t *q, mblk_t *mp)
--- 1105,1116 ----
  
  out:
          mutex_enter(&odd->odd_lock);
          overlay_io_done(odd, OVERLAY_F_IN_TX);
          mutex_exit(&odd->odd_lock);
!         freemsgchain(mp_chain);
!         return (NULL);
  }
  
  /* ARGSUSED */
  static void
  overlay_m_ioctl(void *arg, queue_t *q, mblk_t *mp)