zink: activate conditional render for compute dispatch when necessary

fixes:
KHR-GL46.compute_shader.conditional-dispatching

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15018>

src/gallium/drivers/zink/zink_draw.cpp

@@ -942,6 +942,9 @@ zink_launch_grid(struct pipe_context *pctx, const struct pipe_grid_info *info)
    struct zink_screen *screen = zink_screen(pctx->screen);
    struct zink_batch *batch = &ctx->batch;
 
+   if (ctx->render_condition_active)
+      zink_start_conditional_render(ctx);
+
    update_barriers(ctx, true);
    if (ctx->memory_barrier)
       zink_flush_memory_barrier(ctx, true);