qemu: blockjob: Save status XML when modifying job state

qemu: blockjob: Save status XML when modifying job state

Now that block job data is stored in the status XML portion we need to
make sure that everything which changes the state also saves the status
XML. The job registering function is used while parsing the status XML
so in that case we need to skip the XML saving.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>