Clear the subsystem ref count when shutting down subsystems in the main quit

This prevents dependent subsystems from being deinitialized multiple times

src/SDL.c

@@ -131,8 +131,12 @@ static void SDL_DecrementSubsystemRefCount(Uint32 subsystem)
 {
     const int subsystem_index = SDL_MostSignificantBitIndex32(subsystem);
     if ((subsystem_index >= 0) && (SDL_SubsystemRefCount[subsystem_index] > 0)) {
+        if (SDL_bInMainQuit) {
+            SDL_SubsystemRefCount[subsystem_index] = 0;
+        } else {
             --SDL_SubsystemRefCount[subsystem_index];
         }
+    }
 }
 
 /* Private helper to check if a system needs init. */