When RFC 8981 obsoleted RFC 4941 the terminology changed from
"privacy extensions" to "temporary address extensions"
Change ifconfig(8) to output temporary after temporary addresses and
add "temporary" option which is an alias for autoconfprivacy for now.
Also make AUTOCONF6TEMP a positiv flag that is set by default.
Previously the negative flag "INET6_NOPRIVACY" was set when privacy
addresses were disabled. This makes the flags output less ugly and
will allow us to disable autoconf addresses while having temporary
addresses enabled in the future.
More work is needed in slaacd.
input benno, jmc, deraadt
previous verison OK benno
OK jmc, kn