Without this, `nmcli device modify "$DEVICE"` leads to a crash. At least
since commit c5d45848dd ('cli: mark argv argument for command line
parsing as const'), when this happens.
That is, because it passes a NULL strv array with argc being set to
zero. nmc_process_connection_properties() is not supposed to access
the array, if there are no elements there.
Fixes: c5d45848dd ('cli: mark argv argument for command line parsing as const')
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/492