qemu: capabilities: Add virtio/vhost {non-}transitional

Add a single QEMU_CAPS_VIRTIO_PCI_TRANSITIONAL that
will be set if any of the following qemu devices are found:

    virtio-blk-pci-transitional
    virtio-blk-pci-non-transitional
    virtio-net-pci-transitional
    virtio-net-pci-non-transitional
    vhost-scsi-pci-transitional
    vhost-scsi-pci-non-transitional
    virtio-rng-pci-transitional
    virtio-rng-pci-non-transitional
    virtio-9p-pci-transitional
    virtio-9p-pci-non-transitional
    virtio-balloon-pci-transitional
    virtio-balloon-pci-non-transitional
    vhost-vsock-pci-transitional
    vhost-vsock-pci-non-transitional
    virtio-input-host-pci-transitional
    virtio-input-host-pci-non-transitional
    virtio-scsi-pci-transitional
    virtio-scsi-pci-non-transitional
    virtio-serial-pci-transitional
    virtio-serial-pci-non-transitional

Reviewed-by: Andrea Bolognani <abologna@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>

tests/qemucapabilitiesdata/caps_4.0.0.riscv32.xml

@@ -160,6 +160,7 @@
   <flag name='egl-headless.rendernode'/>
   <flag name='memory-backend-file.align'/>
   <flag name='memory-backend-file.pmem'/>
+  <flag name='virtio-pci-non-transitional'/>
   <version>3001050</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>0</microcodeVersion>

tests/qemucapabilitiesdata/caps_4.0.0.riscv64.xml

@@ -160,6 +160,7 @@
   <flag name='egl-headless.rendernode'/>
   <flag name='memory-backend-file.align'/>
   <flag name='memory-backend-file.pmem'/>
+  <flag name='virtio-pci-non-transitional'/>
   <version>3001050</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>0</microcodeVersion>

tests/qemucapabilitiesdata/caps_4.0.0.x86_64.xml

@@ -205,6 +205,7 @@
   <flag name='memory-backend-file.pmem'/>
   <flag name='nvdimm.unarmed'/>
   <flag name='scsi-disk.device_id'/>
+  <flag name='virtio-pci-non-transitional'/>
   <version>3001050</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>43100758</microcodeVersion>