Function drmgr_unregister_low_on_memory_event_user_data 

pub unsafe extern "C" fn drmgr_unregister_low_on_memory_event_user_data(
    func: Option<unsafe extern "C" fn(user_data: *mut c_void)>,
) -> bool_

Unregister a callback function that accepts user-data for the low-on-memory event. \return true if the unregistration of \p func is successful.