add hook to ospf&ospf6

[FeiyanLv]

I notice that in OSPF&OSPF6 has less hooks in code,but BGP with much more hooks.If there any problem to add hooks into OSPF&OSPF6?If it's permitted, I want add ospf route change post hook into OSPF and add ospf6 lsa update/delete and ospf6 route change post into OSPF6 as OSPF does.