tools/virtio: add barrier for aarch64

Add barrier for aarch64 for cross compiling, and  most are from Linux Kernel.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20201209084205.24062-4-peng.fan@oss.nxp.com


Signed-off-by: Michael S. Tsirkin <mst@redhat.com>