* GPU: Keep sampled textures without any pool references alive
Occasionally games are very wasteful and clear/write to a texture without ever sampling it. As rendered textures in NVN games seem to all have overlapping memory ranges, the texture will eventually get overwritten.
Normally, this would trigger a removal from the auto delete cache, but a pool entry would keep the texture alive. However, with these textures that are never used, they will get deleted immediately and recreated on the next frame.
This change makes it so the ShortTextureCache can keep textures that have naver had a pool reference alive for a few frames, so they're not constantly being created and deleted.
This improves performance in Zelda BOTW a little.
* Cleanup
