Function imagequant_sys::liq_image_create_custom

pub unsafe extern "C" fn liq_image_create_custom(
    attr: &liq_attr, 
    row_callback: liq_image_get_rgba_row_callback, 
    user_info: *mut c_void, 
    width: c_int, 
    height: c_int, 
    gamma: f64
) -> *mut liq_image