Backporting a small part of the socket.py changes from 2.3: get rid

Backporting a small part of the socket.py changes from 2.3:  get rid
of the socket wrapper __del__ method.  It isn't needed, and it prevents
cyclic structures containing socket objects (primarily on Windows, where
the wrapper is used) from getting garbage-collected.  People running
ZEO tests in Zope under Windows are acutely aware of this, as the
test driver prints an ever-growing gc.garbage list after each test.