Enable 802.1X forwarding for KVM guests

If you are trying to run a virtual machine using libvirt (KVM) with bridged networking on the host, the default configuration for 802.1D MAC bridging doesn’t support forwarding of EAPOL traffic for 802.1X authentication. Running the wpa_supplicant on the VM guest will fail. The following assumes you’ve already configured bridged networking on the VM host…