randomize proxy port to improve chances of unit tests passing

test/setup_transfer.cpp

@@ -161,10 +161,12 @@ void stop_proxy(int port)
 	}
 }
 
-void start_proxy(int port, int proxy_type)
+int start_proxy(int proxy_type)
 {
 	using namespace libtorrent;
 
+	int port = 10000 + (rand() % 50000);
+
 	stop_proxy(port);
 
 	char const* type = "";
@@ -203,6 +205,7 @@ void start_proxy(int port, int proxy_type)
 	fprintf(stderr, "launched\n");
 	// apparently delegate takes a while to open its listen port
 	test_sleep(500);
+	return port;
 }
 
 using namespace libtorrent;