Re: [libvirt] [PATCH 12/13] qemu: only add channel arg to scsi-disk if qemu binary supports it

libvirt enforces bus (channel to qemu) == 0 for those qemu binaries that don't support the channel argument to scsi disk devices, but still adds "channel=0" in those cases. Apparently nobody with a qemu old enough to not support channel ever uses these devices, because they otherwise should get an error. This patch only adds channel when the scsi-disk.channel capability is set for the qemu binary. Most of the change in the patch is updating patches to either 1) remove channel=0 from the .args file of the test, or 2) reposition channel=0 to precede the bus arg (because this makes the code cleaner/simpler) and change the DO_TEST() invocation for the test to add QEMU_CAPS_SCSI_DISK_CHANNEL. I'm uncommitted about whether or not it is worthwhile to push this patch. On one hand, I'm fairly certain this is what is correct; on the other hand nobody has ever complained about it, and at this point almost everyone is using new enough qemu that it supports channel. ---