ospfd: Remove oi field from LSA, have network_lsa_refresh look up when needed

* ospf_lsa.h: (struct ospf_lsa) remove oi pointer
* ospf_lsa.c: (ospf_network_lsa_refresh) instead of keeping a pointer, just
  lookup the oi when it's needed. This decouples network LSA from oi lifetime
  and avoids having to invalidate pointers in LSAs when an oi changes,
  simplifying the code.
2 files changed