add vsock support

[bergwolf]

The PR imports runv changes from hyperhq/runv#411 to add vsock support to hyperd.

vsock support is enabled via EnableVsock=true option in /etc/hyper/config and currently it only supports qemu/libvirt driver and does not work with template enabled.

Hypervisor=qemu
EnableVsock=true

[hypervsock@lib]$sudo hyperctl run -d busybox
POD id is busybox-2866232067
Time to run a POD is 3760 ms
[hypervsock@lib]$ps aux|grep vsock
root      92079 41.7  5.9 847492 106804 ?       Sl   15:42   0:03 /bin/qemu-system-x86_64 -machine pc-i440fx-2.1,accel=kvm,usb=off -global kvm-pit.lost_tick_policy=discard -cpu host -kernel /var/lib/hyper/kernel -initrd /var/lib/hyper/hyper-initrd.img -append console=ttyS0 panic=1 no_timer_check -realtime mlock=off -no-user-config -nodefaults -no-hpet -rtc base=utc,driftfix=slew -no-reboot -display none -boot strict=on -m size=64,slots=1,maxmem=32768M -smp cpus=1,maxcpus=8 -numa node,nodeid=0,cpus=0-7,mem=64 -qmp unix:/var/run/hyper/vm-mZnUhloRut/qmp.sock,server,nowait -serial unix:/var/run/hyper/vm-mZnUhloRut/console.sock,server,nowait -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x2 -device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x3 -chardev socket,id=charch0,path=/var/run/hyper/vm-mZnUhloRut/hyper.sock,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charch0,id=channel0,name=sh.hyper.channel.0 -chardev socket,id=charch1,path=/var/run/hyper/vm-mZnUhloRut/tty.sock,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=2,chardev=charch1,id=channel1,name=sh.hyper.channel.1 -fsdev local,id=virtio9p,path=/var/run/hyper/vm-mZnUhloRut/share_dir,security_model=none -device virtio-9p-pci,fsdev=virtio9p,mount_tag=share_dir -daemonize -pidfile /var/run/hyper/vm-mZnUhloRut/pidfile -D /var/log/hyper/qemu/vm-mZnUhloRut.log
-device vhost-vsock-pci,id=vsock0,bus=pci.0,addr=5,guest-cid=1025
[hypervsock@lib]$sudo hyperctl exec -t busybox-2866232067 lsmod
vmw_vsock_virtio_transport 5033 4 - Live 0xffffffffa0014000
vmw_vsock_virtio_transport_common 9538 1 vmw_vsock_virtio_transport, Live 0xffffffffa000b000
vsock 23269 6 vmw_vsock_virtio_transport,vmw_vsock_virtio_transport_common, Live 0xffffffffa0000000

[bergwolf]

travis (https://travis-ci.org/hyperhq/hyperd/builds/204104859) shows #1196 passed but somehow the result was not showed here.