Fix EpollEvent structure declaration.

This fixes strange epoll results (yielding unknown file descriptors).
There is no explanation as of why it worked in 64bits until now.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@1553 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/epoll.py

@@ -61,6 +61,7 @@ class EpollData(Union):
 class EpollEvent(Structure):
     _fields_ = [("events", c_uint32),
                 ("data", EpollData)]
+    _pack_ = 1
 
 class Epoll(object):
     efd = -1