util/ra: use adjacency matrix for undirected graph

util/ra: use adjacency matrix for undirected graph

Since this graph is actually not oriented, its adjacency matrix can be
represented using less than half bits required by full adjacency matrix.
It reduces memory consumption and number of cache misses. It also simplifies
logic of growing this matrix - no need to touch adjacency bits for previously
allocated number of nodes.

Move adjacency bits from nodes to graph to reduce the number of allocations.

No changes to shader-db.

Reviewed-by: Emma Anholt <emma@anholt.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Signed-off-by: Kostiantyn Lazukin <kostiantyn.lazukin@globallogic.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14189>