Need a way to terminate a build such that it never runs again

[LaMont Jones]

Every now and then (ok, far too often) a source package is uploaded that kills build machines, generally by going into an infinite loop with output. When this is on an archive builder, it's not so bad - we can get in and affect the build directly and cause it to actually fail. On the ppa builders, this is not really an option - all we can do is yank the buildd out from under the build, which just means that the build gets retried if it's not already superseded.

The solution today is an ugly bunch of SQL that should really be turned into a button. Said button should have the characteristics:
1. Anyone who could upload the package should be able to click the "make this build die horribly and never get tried again."
2. For bonus points, a launchpad-admin (and definitely NOT merely an uploader) should be able to effectively undo the deletion, to allow us to recover from when it's accidentally pushed. if this part is hard, we can ignore it and people can just re-upload when they've made a mistake like that.

thanks,
lamont