kqueue(2) is currently broken when used with /dev/null and a few other

devices.

An upcoming fix for some problems with the client stdout/stderr handling
relies on it working, so make tmux force libevent to use poll(2) via
EVENT_NOKQUEUE, until we have fixed kqueue.

tmux.c

@@ -532,7 +532,10 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (setenv("EVENT_NOKQUEUE", "1", 1) != 0)
+		fatal("setenv");
 	ev_base = event_init();
+	unsetenv("EVENT_NOKQUEUE");
 	set_signals(main_signal);
 
 	/* Initialise the client socket/start the server. */