[libvirt] Qemu Commandline options are ignored during migration

[Tim Foerster]

Heyho Guys,

The domain defintion xml allows to extend the qemu command.

For example:

```
  <qemu:commandline>
    <qemu:arg value='-cpu'/>
    <qemu:arg value='SandyBridge,-kvm_steal_time'/>
  </qemu:commandline>
```

The options are correctly passed on startup, but the migration will
ignore them. The desination xml is dumped with the flags 1|2|8. (secure,
inactive and migrateable)

`secure` flag is required to keep vnc passwords, and inactive to keep
the metadata section. But i also mentioned that qemu:commandline section
needs inactive flag too.

-- 

Tim Foerster