Remove ip6_getdstifaddr() and all functions to work with auxiliary data.
It isn't safe to keep unreferenced ifaddrs. Use in6ifa_ifwithaddr() to
determine ifaddr corresponding to destination address. Since currently
we keep addresses with embedded scope zone, in6ifa_ifwithaddr is called
with zero zoneid and marked with XXX.

Also remove route and lle lookups from ip6_input. Use in6ifa_ifwithaddr()
instead.

Sponsored by:	Yandex LLC


git-svn-id: svn+ssh://svn.freebsd.org/base/head@274300 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f