As a longer-term solution, I would suggest adding cross-posting as an explicit close reason. This is already being used on Unix & Linux, listed under Off Topic.
This question has been posted on multiple sites. Cross-posting is strongly discouraged; see the help center and community FAQ for more information.
It seems to work well. Off-topic, cross-posted questions are generally closed soon after I flag them as such and I think this would be a useful feature for Server Fault.