We previously assumed that if the -device option existed in qemu, that
-nodefconfig would also exist. It turns out that isn't the case, as
demonstrated by qemu-kvm-0.12.3 in Fedora 13.

*/src/qemu/qemu_conf.[hc] - add a new QEMUD_CMD_FLAG, set it via the
                            help output, and check it before adding
                            -nodefconfig to the qemu commandline.