Make the NDS teardown more robust (#1798)

* Make cleanup a little more robust to mitigate undefined behavior

- Add some null checks before cleaning up the GPU3D renderer
- Make sure that all deleted objects are null
- Move cleanup logic out of an assert call
- Note that deleting a null pointer is a no-op, so there's no need to check for null beforehand
- Use RAII for GLCompositor instead of Init/DeInit methods

* Replace a DeInit call that I missed

* Make ARMJIT_Memory less likely to generate errors

- Set FastMem7/9Start to nullptr at the end
- Only close and unmap the file if it's initialized

* Make Renderer3D manage its resources with RAII

* Don't try to deallocate frontend resources that aren't loaded

* Make ARMJIT_Memory::DeInit more robust on the Switch

* Reset MemoryFile on Windows to INVALID_HANDLE_VALUE, not nullptr

- There is a difference

* Don't explicitly store a Valid state in GLCompositor or the 3D renderers

- Instead, create them with static methods while making the actual constructors private

* Make initialization of OpenGL resources fail if OpenGL isn't loaded

* assert that OpenGL is loaded instead of returning failure

src/frontend/qt_sdl/AudioInOut.cpp

@@ -334,12 +334,17 @@ void Init()
 void DeInit()
 {
     if (audioDevice) SDL_CloseAudioDevice(audioDevice);
+    audioDevice = 0;
     MicClose();
 
-    SDL_DestroyCond(audioSync);
-    SDL_DestroyMutex(audioSyncLock);
+    if (audioSync) SDL_DestroyCond(audioSync);
+    audioSync = nullptr;
+
+    if (audioSyncLock) SDL_DestroyMutex(audioSyncLock);
+    audioSyncLock = nullptr;
 
     if (micWavBuffer) delete[] micWavBuffer;
+    micWavBuffer = nullptr;
 }
 
 void AudioSync()

src/frontend/qt_sdl/LocalMP.cpp

@@ -297,16 +297,21 @@ bool Init()
 
 void DeInit()
 {
-    MPQueue->lock();
-    MPQueueHeader* header = (MPQueueHeader*)MPQueue->data();
-    header->ConnectedBitmask &= ~(1 << InstanceID);
-    header->InstanceBitmask &= ~(1 << InstanceID);
-    header->NumInstances--;
-    MPQueue->unlock();
+    if (MPQueue)
+    {
+        MPQueue->lock();
+        MPQueueHeader* header = (MPQueueHeader*)MPQueue->data();
+        header->ConnectedBitmask &= ~(1 << InstanceID);
+        header->InstanceBitmask &= ~(1 << InstanceID);
+        header->NumInstances--;
+        MPQueue->unlock();
 
-    SemPoolDeinit();
+        SemPoolDeinit();
 
-    MPQueue->detach();
+        MPQueue->detach();
+    }
+
+    MPQueue = nullptr;
     delete MPQueue;
 }