nvk: Allocate from holes in descriptor set pools
This fixes artifacts on godot's vulkan backend,which doesn't handle VK_ERROR_OUT_OF_POOL_MEMORY well.
Due to an influx of spam, we have had to impose restrictions on new accounts. Please see this wiki page for instructions on how to get full permissions. Sorry for the inconvenience.
This fixes artifacts on godot's vulkan backend,which doesn't handle VK_ERROR_OUT_OF_POOL_MEMORY well.