[PATCH] epoll: fix delayed initialization bug

Al found a potential problem in epoll_create(), where the
file->private_data member was set after fd_install().  This is obviously
wrong since another thread might do a close() on that fd# before we set the
file->private_data member.  This goes over 2.6.13 and passes a few basic
tests I've done here.

(akpm: snuck in a kzalloc() cleanup too)

Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>