libudev: fix udev_queue_get_queue_is_empty() logic

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
libudev: queue provide file descriptor to watch busy event queue

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
libudev: queue - watch entire directory to allow the re-use of the watch descriptor

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
rules: don't enable usb pm for Avocent devices

The Avocent KVM over IP devices doesn't work correctly with USB power
management enabled.

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>