We can just place the set structures inside nir_block.
This reduces the number of ralloc calls by 6.7% when compiling Heaven
shaders with radeonsi+ACO using a release build (i.e. not including
nir_validate set allocations, which are also removed).
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>
Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36728>