llvmpipe: handle multisample early depth test/late depth write

llvmpipe: handle multisample early depth test/late depth write

A set of values have to be passed from the early depth test to the
late depth write, when multisampling is enabled, a range of those
values have to be stored between stages, so create storage for them
and pass the values through the storage.

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4122>