zink: use gallium aux/pb
Currently we just allocate memory every time it's needed for resources. I have some patches in my branch which implement very naive caching to store extra copies of resources, which sort of solves the case where the exact same resource is allocated/deallocated over and over (and is great in perf for those specific cases), but aux/pipebuffer is a much better (and much, much more complex) implementation of that which we could be using for our mem allocations--but not the actual image/buffer objects, just the
Probably this can be done at any time since we'll want to have a separate
zink_pb.c file or somesuch to isolate it all.