Re: [PATCH v4 0/5] MR464: vkd3d-shader/spirv: Declare I/O registers from the signature.

[Giovanni Mascellani (＠giomasce)]

I discovered a similar instance in `test_shader_eval_attribute()`:
```
VUID-RuntimeSpirv-OpTypeVector-06816(ERROR / SPEC): msgNum: 79036675 - Validation Error: [ VUID-RuntimeSpirv-OpTypeVector-06816 ] Object 0: handle = 0x240000000024, type = VK_OBJECT_TYPE_SHADER_MODULE; Object 1: handle = 0x250000000025, type = VK_OBJECT_TYPE_SHADER_MODULE; | MessageID = 0x4b60103 | vkCreateGraphicsPipelines(): pCreateInfos[0] starting at Location 1 Component 0 the Output (VK_SHADER_STAGE_VERTEX_BIT) has a Vec4 while Input (VK_SHADER_STAGE_FRAGMENT_BIT) as a Vec2. Enable VK_KHR_maintenance4 device extension to allow relaxed interface matching between input and output vectors. The Vulkan spec states: Any OpTypeVector output interface variables must not have a higher Component Count than a matching OpTypeVector input interface variable (https://www.khronos.org/registry/vulkan/specs/1.2/html/vkspec.html#VUID-Runt...)
```

Here again two different semantics are merged in the VS but not in the PS, which trigger a similar error. And again this seems to cause a failure in MoltenVK.

The difference is that this doesn't seem to be related to 66cb2815f0662713c3255113255cfd7cf5e406fb, it also happened before. But maybe it's useful to know anyway.