ospfd: Remove the blocking of opaque LSAs origination & flooding 'optimisation'

ospfd: Remove the blocking of opaque LSAs origination & flooding 'optimisation'

* Opaque support contains some kind of hack/optimisation to
  origination/flooding to suppress some origins/floods until an opaque LS
  Acks are received.  Previous versions of the code have already been shown
  to have bugs in them (see e16fd8a5, e.g.). It seems over-complex and fragile,
  plus its conceptually the wrong place to try implement flooding hacks that,
  AFAICT, do not depend particularly on the semantics of opaque LSA.

  Nuke.

Tested-by: Olivier Dugeon <olivier.dugeon@orange.com>