Fix layout for structured buffers of matrices (#1184)

When using row-major layout (via command-line or API option), the following sort of declaration:

```hlsl
StructuredBuffer<float4x4> gBuffer;

... gBuffer[i] ...
```

Generates unexpected results when compiled to DXBC via fxc or DXIL via dxc, because the fxc/dxc compilers do not respect the matrix layout mode in this specific case (a structured buffer of matrices). Instead, they always use column-major layout, even if row-major was requested by the user.

A user can work around this behavior by wrapping the matrix in a `struct`:

```hlsl
struct Wrapper { float4x4 wrapped; }
SturcturedBuffer<Wrapper> gBuffer;

... gBuffer[i].wrapped ...
```

This change simply automates that workaround when compiling for an HLSL-based downstream compiler, so that we get the same behavior across all our backends.

The change adds a test case to confirm the behavior across multiple targets, but it turns out we also had a test checked in that confirmed the buggy (or at least surprising) fxc/dxc behavior, so that one had its baselines changed and can work as a regression test for this fix as well.

0 files changed, 0 insertions, 0 deletions