Event: add dummy _reset_internal_locks
WIP pypy support

based on https://github.com/gevent-on-pypy/pypycore/commit/f04a41c0eacfab2662e24291cd63859ecea2f9fe written by

Ralf Schmitt
Lucas Clemente Vella
@hasenj
Armin Rigo
greentest.py: temporarily exclude corecffi from checks