Function lv_cache_set_compare_cb 

pub unsafe extern "C" fn lv_cache_set_compare_cb(
    cache: *mut lv_cache_t,
    compare_cb: lv_cache_compare_cb_t,
    user_data: *mut c_void,
)

Set the compare callback of the cache. @param cache The cache object pointer to set the compare callback. @param compare_cb The compare callback to set. @param user_data A user data pointer.