[Libguestfs] [PATCH] appliance: Pass root=UUID=... to supermin.

[Richard W.M. Jones]

By passing root=UUID=... to supermin, we make the appliance boot
process less sensitive to the non-deterministic process of scanning
SCSI disks (of which much more to come).

This patch should be tested alongside the supermin patch posted here:

  https://www.redhat.com/archives/libguestfs/2017-April/msg00174.html

which in turn requires this supermin patch series:

  https://www.redhat.com/archives/libguestfs/2017-April/msg00162.html

This will require that libguestfs & supermin are upgraded in step in
all downstream distributions, and will also invalidate all binary
appliances (although we don't ship a binary appliance for 1.37 so
that's not a problem).

Rich.