runqemu: Allow unique network interface MAC addresses

Current qemu instances all share the same MAC address. This shouldn't be an issue as they are all on separate network interfaces, however on the slight chance this is causing problems, its easy enough to ensure we use unique MAC addresses based on the IP numbers we assign.

index df76ee6..da59c33 100644
@@ -16,7 +16,7 @@ QB_MACHINE = "-machine virt"

 QB_CPU = "-cpu cortex-a57"
 QB_KERNEL_CMDLINE_APPEND = "console=ttyAMA0,38400"
 QB_OPT_APPEND = "-show-cursor"
-QB_TAP_OPT = "-netdev tap,id=net0,ifname=@TAP@,script=no,downscript=no -device virtio-net-device,netdev=net0" +QB_TAP_OPT = "-netdev tap,id=net0,ifname=@TAP@,script=no,downscript=no -device virtio-net-device,netdev=net0,mac=@MAC@" QB_SLIRP_OPT = "-netdev user,id=net0 -device virtio-net-device,netdev=net0"
 QB_ROOTFS_OPT = "-drive id=disk0,file=@ROOTFS@,if=none,format=raw -device virtio-blk-device,drive=disk0" QB_SERIAL_OPT = "-device virtio-serial-device -chardev null,id=virtcon -device virtconsole,chardev=virtcon"

index 939c834..e4c8dac 100644
@@ -17,4 +17,4 @@ QB_MACHINE = "-machine mac99"

 QB_CPU = "-cpu G4"
 QB_KERNEL_CMDLINE_APPEND = "console=ttyS0 console=tty"
 QB_OPT_APPEND = "-show-cursor -usb -usbdevice tablet"
-QB_TAP_OPT = "-netdev tap,id=net0,ifname=@TAP@,script=no,downscript=no -device virtio-net-pci,netdev=net0" +QB_TAP_OPT = "-netdev tap,id=net0,ifname=@TAP@,script=no,downscript=no -device virtio-net-pci,netdev=net0,mac=@MAC@"

index 867e818..2b5e588 100755
@@ -681,11 +681,12 @@ class BaseConfig(object):

         if self.fstype == 'nfs':
             self.setup_nfs()
         self.kernel_cmdline_script += " ip=192.168.7.%s::192.168.7.%s:255.255.255.0" % (n2, n1)
+        mac = "52:54:00:12:34:%02x" % n2
         qb_tap_opt = self.get('QB_TAP_OPT')
         if qb_tap_opt:
-            qemu_tap_opt = qb_tap_opt.replace('@TAP@', tap)
+            qemu_tap_opt = qb_tap_opt.replace('@TAP@', tap).replace('@MAC@', mac)
         else:
-            qemu_tap_opt = "-net nic,model=virtio -net tap,vlan=0,ifname=%s,script=no,downscript=no" % self.tap +            qemu_tap_opt = "-net nic,model=virtio,mac=%s -net tap,vlan=0,ifname=%s,script=no,downscript=no" % (mac, self.tap)
         if self.vhost_enabled:
             qemu_tap_opt += ',vhost=on'