traceroute.py: make traceroute6 work on both MacOS and Linux.
traceroute.py: make traceroute6 work on both MacOS and Linux.

The "-l" option works differently between the two versions.

shineyear/catawampus,ankurjimmy/catawampus,ultilix/catawampus,pombredanne/catawampus,ankurjimmy/catawampus,shineyear/catawampus,ultilix/catawampus,pombredanne/catawampus