textproc/py-xml: remove port
This package has been included into python standard library since python 2.2 or
2.0, but some of our ports used apis not available in stock python xml package.
Now all the issue are fixed and we can finally remove this port.
It is dead upstream and because of it's invasive nature it may break innocent
ports while installed (there were known issues for Eric and Docutils), so it was
removed in most distributions years ago. There is comprehensive summary on
reasons why PyXML was removed at Fedora Project [1]. The same reasons are also
applicable to our tree.