qemu: Fix crash in tunnelled migration
qemu: Fix crash in tunnelled migration

Any attempt to start a tunnelled migration with libvirtd that supports
RDMA migration (specifically commit v1.2.8-226-ged22a47) crashes
libvirtd on the destination host.

The crash is inevitable because qemuMigrationPrepareAny is always called
with NULL protocol in case of tunnelled migration.

https://bugzilla.redhat.com/show_bug.cgi?id=1147331
Signed-off-by: Jiri Denemark <62bdf77dc47919a4d59a91822129d14633cfca81@redhat.com>

datto/libvirt,rlaager/libvirt,taget/libvirt,shugaoye/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,datto/libvirt,olafhering/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,andreabolognani/libvirt,eskultety/libvirt,elmarco/libvirt,taget/libvirt,jfehlig/libvirt,nertpinx/libvirt,eskultety/libvirt,elmarco/libvirt,andreabolognani/libvirt,olafhering/libvirt,elmarco/libvirt,libvirt/libvirt,libvirt/libvirt,jardasgit/libvirt,eskultety/libvirt,nertpinx/libvirt,rlaager/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,elmarco/libvirt,jardasgit/libvirt,agx/libvirt,andreabolognani/libvirt,datto/libvirt,nertpinx/libvirt,zippy2/libvirt,rlaager/libvirt,shugaoye/libvirt,libvirt/libvirt,jfehlig/libvirt,crobinso/libvirt,rlaager/libvirt,agx/libvirt,crobinso/libvirt,VenkatDatta/libvirt,VenkatDatta/libvirt,taget/libvirt,datto/libvirt,jardasgit/libvirt,VenkatDatta/libvirt,olafhering/libvirt,jardasgit/libvirt,agx/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,elmarco/libvirt,VenkatDatta/libvirt,eskultety/libvirt,fabianfreyer/libvirt,crobinso/libvirt,shugaoye/libvirt,agx/libvirt,olafhering/libvirt,zippy2/libvirt,crobinso/libvirt,eskultety/libvirt,shugaoye/libvirt,rlaager/libvirt,zippy2/libvirt,libvirt/libvirt,zippy2/libvirt,fabianfreyer/libvirt,datto/libvirt,shugaoye/libvirt,jfehlig/libvirt,agx/libvirt,taget/libvirt,taget/libvirt,nertpinx/libvirt