qemu: blockjob: Emit VIR_DOMAIN_EVENT_ID_BLOCK_JOB only for local disks
qemu: blockjob: Emit VIR_DOMAIN_EVENT_ID_BLOCK_JOB only for local disks

The event reports the disk path to identify the disk which makes sense
only for local disks. Additionally network backed disks like NBD don't
need to have a path so the callback would return NULL.

Report VIR_DOMAIN_EVENT_ID_BLOCK_JOB only for non-empty local disks.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

andreabolognani/libvirt,nertpinx/libvirt,olafhering/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,eskultety/libvirt,libvirt/libvirt,libvirt/libvirt,zippy2/libvirt,crobinso/libvirt,eskultety/libvirt,crobinso/libvirt,andreabolognani/libvirt,jardasgit/libvirt,nertpinx/libvirt,zippy2/libvirt,jfehlig/libvirt,eskultety/libvirt,crobinso/libvirt,eskultety/libvirt,zippy2/libvirt,olafhering/libvirt,jardasgit/libvirt,jardasgit/libvirt,jfehlig/libvirt,jfehlig/libvirt,libvirt/libvirt,fabianfreyer/libvirt,zippy2/libvirt,jardasgit/libvirt,olafhering/libvirt,nertpinx/libvirt,eskultety/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,libvirt/libvirt,olafhering/libvirt,crobinso/libvirt,andreabolognani/libvirt,nertpinx/libvirt,nertpinx/libvirt