qt: Disable OpenGL 3.0 renderer for macOS.

Until it's figured out, macOS has dummy implementation to keep it
building.

src/qt/qt_mainwindow.cpp

@@ -231,6 +231,9 @@ MainWindow::MainWindow(QWidget *parent) :
     ui->actionHardware_Renderer_OpenGL_ES->setVisible(QOpenGLContext::openGLModuleType() == QOpenGLContext::LibGLES);
     if (QOpenGLContext::openGLModuleType() != QOpenGLContext::LibGLES && vid_api == 2) vid_api = 1;
 #endif
+#ifdef Q_OS_MACOS
+    ui->actionOpenGL_3_0_Core->setVisible(false);
+#endif
 
     if (QApplication::platformName().contains("eglfs") && vid_api >= 1) {
         fprintf(stderr, "OpenGL renderers are unsupported on EGLFS.\n");