Add FPS to SDL title bar

Also fix a small issue with incorrect shutdown ordering in SDL.
Previously the system would still be running so the telemetry task
didn't launch and detached_tasks would assert(count == 0)

src/yuzu_cmd/emu_window/emu_window_sdl2.h

@@ -60,4 +60,7 @@ protected:
 
     /// Internal SDL2 render window
     SDL_Window* render_window;
+
+    /// Keeps track of how often to update the title bar during gameplay
+    u32 last_time = 0;
 };