ospf: Fix OSPF API and ospf-te LSA refreshers to match recent API change

* ospf_apiserver.{c,h}: (ospf_apiserver_lsa_refresher) refreshers must now
  return the refreshed LSA.
* ospf_te.{c,h}: (ospf_mpls_te_lsa_refresh) ditto
* ospf_api.c: trivial compiler warning fix
4 files changed