Re: [PATCH 0/4] MR260: vkd3d: Prepare for buffering of command list commands.

[Henri Verbeet (＠hverbeet)]

> +    refcount = ID3D12CommandSignature_Release(command_signature);
> +    ok(!refcount, "ID3D12CommandSignature has %u references left.\n", refcount);

This introduces warnings with "make crosstest":
```
<vkd3d>/tests/d3d12.c:24512:19: warning: format ‘%u’ expects argument of type ‘unsigned int’, but argument 4 has type ‘ULONG’ {aka ‘long unsigned int’} [-Wformat=]
     ok(!refcount, "ID3D12CommandSignature has %u references left.\n", refcount);
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  ~~~~~~~~
```

Similar tests typically have explicit casts to "unsigned int".