rem: if (mtx->thread_id != thread_id)
add: if (!mtx->locks || mtx->thread_id != thread_id)
context: LockRecursiveMutex_SDL (RecursiveMutex val){	RecM *mtx = (RecM *)val;	Uint32 thread_id = SDL_ThreadID();	if (mtx->thread_id != thread_id)	{#ifdef TRACK_CONTENTION		if (mtx->thread_id && (mtx->syncClass & TRACK_CONTENTION_CLASSES))		{			fprintf (stderr, "Thread '%s' blocking on '%s'\n", MyThreadName (), mtx->name);		}#endif		while (SDL_mutexP (mtx->mutex))			TaskSwitch_SDL ();		mtx->thread_id = thread_id;	}	mtx->locks++;}