tc: implement a buffer_rebind hook
tc now calculates all the information needed internally for optimally performing buffer rebinds, so a hook should be added to handle this. I'm thinking the prototype would be
void (*buffer_rebind)(struct pipe_context*, struct pipe_resource*, unsigned bind, unsigned slot_mask);
The idea would be that a resource is passed with e.g., buffer_rebind(pipe, resource, PIPE_BIND_VERTEX_BUFFER, 15)
to rebind a resource that's bound as a vertex buffer in slots 0-3.