remote: fix regression in event deregistration
remote: fix regression in event deregistration

Introduced by 7b87a3
When I quit the process which only register VIR_DOMAIN_EVENT_ID_REBOOT,
I got error like:
"libvirt: XML-RPC error : internal error: domain event 0 not registered".
Then I add the following code, it fixed.

Signed-off-by: Zhou Yimin <301f1aa1a5d5742a74cf62f513901bacca83bb66@huawei.com>
Signed-off-by: Eric Blake <a9da18479c871fe903d9590822cfe2629c6a4d11@redhat.com>

jfehlig/libvirt,fabianfreyer/libvirt,rlaager/libvirt,taget/libvirt,rlaager/libvirt,zippy2/libvirt,agx/libvirt,cbosdo/libvirt,elmarco/libvirt,elmarco/libvirt,datto/libvirt,olafhering/libvirt,zippy2/libvirt,cbosdo/libvirt,datto/libvirt,zhlcindy/libvirt-1.1.4-maintain,taget/libvirt,libvirt/libvirt,libvirt/libvirt,libvirt/libvirt,VenkatDatta/libvirt,VenkatDatta/libvirt,shugaoye/libvirt,shugaoye/libvirt,jfehlig/libvirt,shugaoye/libvirt,zippy2/libvirt,olafhering/libvirt,cbosdo/libvirt,datto/libvirt,agx/libvirt,jardasgit/libvirt,rlaager/libvirt,zhlcindy/libvirt-1.1.4-maintain,andreabolognani/libvirt,libvirt/libvirt,cbosdo/libvirt,taget/libvirt,agx/libvirt,eskultety/libvirt,datto/libvirt,datto/libvirt,andreabolognani/libvirt,nertpinx/libvirt,crobinso/libvirt,eskultety/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,zhlcindy/libvirt-1.1.4-maintain,rlaager/libvirt,zhlcindy/libvirt-1.1.4-maintain,olafhering/libvirt,jfehlig/libvirt,rlaager/libvirt,elmarco/libvirt,taget/libvirt,fabianfreyer/libvirt,elmarco/libvirt,agx/libvirt,jardasgit/libvirt,jfehlig/libvirt,nertpinx/libvirt,jardasgit/libvirt,nertpinx/libvirt,VenkatDatta/libvirt,crobinso/libvirt,zhlcindy/libvirt-1.1.4-maintain,eskultety/libvirt,taget/libvirt,zippy2/libvirt,andreabolognani/libvirt,jardasgit/libvirt,eskultety/libvirt,fabianfreyer/libvirt,crobinso/libvirt,VenkatDatta/libvirt,nertpinx/libvirt,agx/libvirt,cbosdo/libvirt,shugaoye/libvirt,andreabolognani/libvirt,elmarco/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,shugaoye/libvirt,nertpinx/libvirt,olafhering/libvirt,eskultety/libvirt,crobinso/libvirt