Function drmgr_unregister_thread_exit_event 

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

Unregister a callback function for the thread exit event. \return true if unregistration is successful and false if it is not (e.g., \p func was not registered).