[gpu] Destroy GPU thread after all non-trivial members had been destroyed (#4368)

Should help fix any game hangs after closing the emulator, or sporadic hangs when restarting.

Signed-off-by: lizzie <lizzie@eden-emu.dev>

- [x] I have read and followed the [Contribution Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/CONTRIBUTING.md#code-contributions).
- [x] I have read and followed the [AI Policy](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/AI.md)
- [x] I have read and followed the [Coding Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/Coding.md) to the best of my ability.

-------------------

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4368
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Reviewed-by: Maufeat <sahyno1996@gmail.com>

src/video_core/gpu.cpp

@@ -55,11 +55,11 @@ constexpr u64 GpuClockMultiplier(Settings::GpuClock clock) {
 
 struct GPU::Impl {
     explicit Impl(Core::System& system_, bool is_async_, bool use_nvdec_)
-        : system{system_}
+        : gpu_thread{system_}
+        , system{system_}
         , use_nvdec{use_nvdec_}
         , shader_notify()
         , is_async{is_async_}
-        , gpu_thread{system_}
     {}
 
     ~Impl() = default;
@@ -301,6 +301,10 @@ struct GPU::Impl {
         return out;
     }
 
+    // Destruction of thread must be done before all (non trivial)
+    // previous members has been destroyed
+    VideoCommon::GPUThread::ThreadManager gpu_thread;
+
     Core::System& system;
 
     std::unique_ptr<VideoCore::RendererBase> renderer;
@@ -329,7 +333,6 @@ struct GPU::Impl {
 
     const bool is_async;
 
-    VideoCommon::GPUThread::ThreadManager gpu_thread;
     std::unique_ptr<Core::Frontend::GraphicsContext> cpu_context;
 
     Tegra::Control::Scheduler scheduler;