Convert tests/virtio-rng-test in qgraph test node,
virtio-rng-test. This test consumes a virtio-rng interface
and checks that its function return the expected values.
Some functions are implemented only for virtio-rng-pci, so they
don't consume virtio-rng, but virtio-rng-pci
Note that this test does not allocate any virtio-rng structure,
it's all done by the qtest walking graph mechanism
Signed-off-by: Emanuele Giuseppe Esposito <e.emanuelegiuseppe@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>