gallium: expand pipe_grid_info to handle task/mesh.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23291>

src/gallium/frontends/rusticl/mesa/pipe/context.rs

@@ -396,6 +396,10 @@ impl PipeContext {
             grid_base: [0; 3],
             indirect: ptr::null_mut(),
             indirect_offset: 0,
+            indirect_stride: 0,
+            draw_count: 0,
+            indirect_draw_count_offset: 0,
+            indirect_draw_count: ptr::null_mut(),
         };
         unsafe { self.pipe.as_ref().launch_grid.unwrap()(self.pipe.as_ptr(), &info) }
     }

src/gallium/include/pipe/p_state.h

@@ -1026,6 +1026,11 @@ struct pipe_grid_info
     */
    struct pipe_resource *indirect;
    unsigned indirect_offset; /**< must be 4 byte aligned */
+   unsigned indirect_stride;
+   /* draw related members are for task/mesh shaders */
+   unsigned draw_count;
+   unsigned indirect_draw_count_offset;
+   struct pipe_resource *indirect_draw_count;
 };
 
 /**