Fixes http://bugzilla.kernel.org/show_bug.cgi?id=7371

sys_epoll_pwait needs to be listed as a conditional (weak)
entry point for CONFIG_EPOLL=n.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>