Function _hb_ot_shape_fallback_spaces 

pub fn _hb_ot_shape_fallback_spaces<'a, 'x>(
    plan: &'a hb_ot_shape_plan_t,
    face: &'a hb_font_t<'a>,
    buffer: &'x mut hb_buffer_t,
    font_funcs: &'x mut FontFuncsDispatch<'a, '_>,
)