core: Don't actually start the http server unless we've specified a port or are asking for a port to be determined and written to file.

core/core.js

@@ -844,6 +844,7 @@ loadSettings()
 			httpd.set_http_redirect(settings.http_redirect);
 		}
 		httpd.all('/app/socket', app.socket);
+		if (tildefriends.http_port > 0 || tildefriends.args.out_http_port_file) {
 			let port = httpd.start(tildefriends.http_port);
 			if (tildefriends.args.out_http_port_file) {
 				print('Writing the port file.');
@@ -862,6 +863,7 @@ loadSettings()
 						print('Failed to write the port file.');
 					});
 			}
+		}
 
 		if (tildefriends.https_port) {
 			async function start_tls() {