*-graveyard ports retired

[Joshua Root]

The p5-graveyard and py-graveyard ports have been removed as they no
longer serve a useful purpose. The buildbot skips replaced ports
automatically and thus doesn't generate the error reports that motivated
the creation of the graveyards.

If you believe that setting replacements is useful for the users of your
module port, you can do so in the individual portfile. Existing
replacements have been moved to their portfiles of origin.

- Josh