Add more random-number noise collection calls.

Mostly on the Unix side: there are lots of places the Windows code was
collecting noise that the corresponding Unix/GTK code wasn't bothering
to, such as mouse movements, keystrokes and various network events.
Also, both platforms had forgotten to collect noise when reading data
from a pipe to a local proxy process, even though in that
configuration that's morally equivalent to the network packet timings
that we'd normally be collecting from.

unix/uxfdsock.c

@@ -167,6 +167,7 @@ static int fdsocket_try_send(FdSocket *fds)
 
 	bufchain_prefix(&fds->pending_output_data, &data, &len);
 	ret = write(fds->outfd, data, len);
+        noise_ultralight(ret);
 	if (ret < 0 && errno != EWOULDBLOCK) {
             if (!fds->pending_error) {
                 fds->pending_error = errno;