Fix build of test_tracker_manager with -Dlogging=OFF.

aux::session_logger is only defined when logging or asserts are enabled.

--- a/test/test_tracker_manager.cpp
+++ b/test/test_tracker_manager.cpp
@@ -18,7 +18,11 @@
 using namespace lt::aux;
 using namespace std::placeholders;
 
-struct tracker_manager_handler : aux::session_logger {
+struct tracker_manager_handler
+#if !defined TORRENT_DISABLE_LOGGING || TORRENT_USE_ASSERTS
+	: aux::session_logger
+#endif
+{
 
 	tracker_manager_handler(io_context& ios, aux::session_settings& sett)
 		: m_host_resolver(ios)