Sticky Hop-by-Hop/Destination options un-settable: hardcoded priv=0 always returns EPERM for root

Summary

ip6_pcbopt(:2019) hardcodes priv=0. IPV6_HOPOPTS/DSTOPTS in ip6_setpktoption check if(!priv)return(EPERM). Root can NEVER set sticky ext headers via setsockopt. RFC 3542 non-conformance. Overly restrictive not bypass. Sendmsg cmsg path unaffected.