Backport libvirt / libxl PV console fix

[George Dunlap]

Another issue I ran into using virt-installer with libvirt/libxl in
14.04 was this:

http://pastebin.com/6pbS6Db7

# virt-install --connect=xen:/// --name u14.04 --ram 1024 --disk
U1L1.img,size=2 --location
http://ftp.ubuntu.com/ubuntu/dists/raring/main/installer-amd64/

Starting install...
Retrieving file MANIFEST...
                        | 2.1 kB     00:00 ...
Retrieving file MANIFEST...
                        | 2.1 kB     00:00 ...
Retrieving file vmlinuz...
                        |  10 MB     00:00 ...
Retrieving file initrd.gz...
                        |  36 MB     02:34 ...
Creating storage file U1L1.img
                        | 2.0 GB     00:00
Creating domain...
                        |    0 B     00:03
Connected to domain u14.04
Escape character is ^]
error: internal error: cannot find character device <null>

It turns out this was fixed in libvirt 1.2.4; c/s
657cb1e44d90bab451256616f9d98fb4439a080c

(You can browse the commit here:
http://libvirt.org/git/?p=libvirt.git;a=commit;h=657cb1e44d90bab451256616f9d98fb4439a080c
)

Would it be possible to backport that change into 14.04, so
virt-install can be used to install PV guests?

Thanks!
 -George