Remove cancel for feedback thread to get rid of resource error.

src/prrt/socket.c

@@ -186,7 +186,6 @@ int PrrtSocket_interrupt(PrrtSocket *sock_ptr) {
     }
 
     if (sock_ptr->receiveFeedbackThread != 0) {
-        check(pthread_cancel(sock_ptr->receiveFeedbackThread) == 0, "Cancel failed.");
         check(pthread_join(sock_ptr->receiveFeedbackThread, res) == 0, "Join failed.");
 
         sock_ptr->receiveFeedbackThread = 0;