net-misc/iputils: rename USE=traceroute to USE=traceroute6 and mark as deprecated

net-misc/iputils: rename USE=traceroute to USE=traceroute6 and mark as deprecated

iputils always did only provide traceroute6. Renaming USE flag will clarify
that iputils can't provide normal IPv4 traceroute.

Also, mark USE=traceroute6 as deprecated (in metadata.xml). See Link 1.

Please use net-analyzer/traceroute for traceroute and traceroute6.

Link 1: https://github.com/iputils/iputils/issues/166

Package-Manager: Portage-2.3.62, Repoman-2.3.12
Signed-off-by: Thomas Deutschmann <whissi@gentoo.org>