qemu: Block migration when transient disk option is enabled
qemu: Block migration when transient disk option is enabled

Block migration when transient disk option is enabled to simplify the
handling of the overlay files.

Signed-off-by: Masayoshi Mizuma <d5fddbc10d7d0c19347bebdeca1e9c9f92c33d10@jp.fujitsu.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>
Tested-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

zippy2/libvirt,jfehlig/libvirt,crobinso/libvirt,zippy2/libvirt,libvirt/libvirt,jardasgit/libvirt,zippy2/libvirt,nertpinx/libvirt,nertpinx/libvirt,olafhering/libvirt,jardasgit/libvirt,nertpinx/libvirt,crobinso/libvirt,zippy2/libvirt,libvirt/libvirt,jardasgit/libvirt,nertpinx/libvirt,libvirt/libvirt,olafhering/libvirt,crobinso/libvirt,jardasgit/libvirt,jfehlig/libvirt,olafhering/libvirt,olafhering/libvirt,jfehlig/libvirt,libvirt/libvirt,jardasgit/libvirt,jfehlig/libvirt,crobinso/libvirt,nertpinx/libvirt