Add QEMU_IFLA_MIN_MTU, QEMU_IFLA_MAX_MTU (from linux v4.19)
    QEMU_IFLA_BRPORT_ISOLATED (from linux v4.18) and
    QEMU_IFLA_BRPORT_BACKUP_PORT (from linux v4.19).

These new types fix this error flow with sudo:
...
Unknown host QEMU_IFLA type: 50
Unknown host QEMU_IFLA type: 51
Unknown QEMU_IFLA_BRPORT type 33
...

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20190206193211.6683-1-laurent@vivier.eu>