libc: stub eventfd()

Needed by boost.asio.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
libc: implement epoll_create1()

It's a superset of epoll_create(), so implement the latter in terms of the
former.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
run: switch to cache=none

More realistic.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
run: allow forwarding tcp ports in run.py

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
imgedit: fix large partition chs

Large partitions set head=254, not 255.  Also be more accurate calculating
the exact point of overflow.
libc: stub epoll EPOLLET treatment

Ignoring EPOLLET will generate more wakeups, but should work with most
applications.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>