MFC r355650:
Follow RFC 4443 p2.2 and always use own addresses for reflected ICMPv6 datagrams. Previously destination address from original datagram was used. That looked confusing, especially in the traceroute6 output. Also honor IPSTEALTH kernel option and do TTL/HLIM decrementing only when stealth mode is disabled. Reported by: Marco van Tol <marco at tols org> Sponsored by: Yandex LLC Differential Revision: https://reviews.freebsd.org/D22631