Function pthread_kill 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn pthread_kill(
    thread: pthread_t,
    sig: c_int,
) -> c_int

See https://pubs.opengroup.org/onlinepubs/9799919799/functions/pthread_kill.html.

Requests that a signal be delivered to the specified thread. It shall not be an error is thread is a zombie thread.

Upon success, returns 0. Upon failure, returns an error number and does not send the signal.