[qt] Use desktop GL always

src/celestia/qt/qtmain.cpp

@@ -66,6 +66,7 @@ int main(int argc, char *argv[])
 
     Q_INIT_RESOURCE(icons);
 
+    QCoreApplication::setAttribute(Qt::AA_UseDesktopOpenGL);
     QCoreApplication::setOrganizationName("Celestia Development Team");
     QCoreApplication::setApplicationName("Celestia QT");