drgui fails to build w/ gcc 9.2.1

ext/drgui/drgui_main_window.cpp: In constructor ‘drgui_main_window_t::drgui_main_window_t(QString, QStringList)’:
/work/drmemory/git/src/dynamorio/ext/drgui/drgui_main_window.cpp:74:43: error: ‘QSignalMapper::QSignalMapper(QObject*)’ is deprecated [-Werror=deprecated-declarations]
   74 |     window_mapper = new QSignalMapper(this);
      |                                           ^