yuzu: Simplify broken Vulkan handling

src/yuzu/main.h

@@ -118,7 +118,7 @@ class GMainWindow : public QMainWindow {
 public:
     void filterBarSetChecked(bool state);
     void UpdateUITheme();
-    explicit GMainWindow();
+    explicit GMainWindow(bool has_broken_vulkan);
     ~GMainWindow() override;
 
     bool DropAction(QDropEvent* event);