qemu: process: Save vcpu ordering information on reconnect

qemu: process: Save vcpu ordering information on reconnect

vCPU ordering information would not be updated if a vCPU emerged or
disappeared during the time libvirtd is not running. This allowed to
create invalid configuration like:

    [...]
    <vcpu id='56' enabled='yes' hotpluggable='yes' order='57'/>
    <vcpu id='57' enabled='yes' hotpluggable='yes' order='58'/>
    <vcpu id='58' enabled='yes' hotpluggable='yes'/>

Call the function that records the information on reconnect.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1451251