[util] cor::copy_* returns changed count

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
[udev] cor-udev library

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
[util] dummy() for copy_apply_if_changed

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>