Flushing the decoder seems to hang when the software fallback is in use, so let the destructor abort callbacks instead

viddec.cpp

@@ -178,8 +178,7 @@ void MoonlightInstance::DispatchGetPicture(uint32_t unused) {
 void MoonlightInstance::VidDecCleanup(void) {
     free(s_DecodeBuffer);
     
-    // Flush and delete the decoder
+    // Delete the decoder
-    g_Instance->m_VideoDecoder->Flush(pp::BlockUntilComplete());
     delete g_Instance->m_VideoDecoder;
     
     // Delete shader programs