gallium: add take_ownership param into set_vertex_buffers to eliminate atomics

There are a few places (mainly u_threaded_context) that do:
   set_vertex_buffers(...);
   for (i = 0; i < count; i++)
      pipe_resource_reference(&buffers[i].resource.buffer, NULL);

set_vertex_buffers increments the reference counts while the loop
decrements them.

This commit eliminates those reference count changes by adding a parameter
into set_vertex_buffers that tells the callee to accept all buffers
without incrementing the reference counts.

AMD Zen benefits from this because it has slow atomics if they come from
different CCXs.

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8298>

src/gallium/drivers/r600/r600_pipe_common.c

@@ -207,7 +207,7 @@ void r600_draw_rectangle(struct blitter_context *blitter,
 	vbuffer.stride = 2 * 4 * sizeof(float); /* vertex size */
 	vbuffer.buffer_offset = offset;
 
-	rctx->b.set_vertex_buffers(&rctx->b, blitter->vb_slot, 1, 0, &vbuffer);
+	rctx->b.set_vertex_buffers(&rctx->b, blitter->vb_slot, 1, 0, false, &vbuffer);
 	util_draw_arrays_instanced(&rctx->b, R600_PRIM_RECTANGLE_LIST, 0, 3,
 				   0, num_instances);
 	pipe_resource_reference(&buf, NULL);