2889eb8bdf
Optimize in6_cksum(), re-ordering work and limiting variable initialization, removing a bzero() for mostly re-initialized struct values, making use of the newly introduced in6_getscope(), as well as converting an if/panic to a KASSERT(). Sponsored by: The FreeBSD Foundation Sponsored by: iXsystems Reviewed by: gnn (as part of the whole) MFC After: 3 days