Add SDL_SHADERCROSS_PROP_HLSL_SKIP_SPIRV_ROUNDTRIP_BOOLEAN to opt out of SPIRV roundtrip

[lammmab]

What?

Some HLSL constructs survive the SPIRV roundtrip without issue, and for those cases the roundtrip adds unnecessary compile time and an extra SPIRV-Cross transformation. This adds a property that lets callers opt out when they know their HLSL is clean.

Changelog

• Added functionality for skipping the SPIRV roundtrip based on the boolean property
• Added SDL_SHADERCROSS_PROP_HLSL_SKIP_SPIRV_ROUNDTRIP_BOOLEAN to SDL_shadercross.h
• Added docstrings explaining the two entry points for the SPIRV roundtrip skip
• Quickly fixed a pre-existing copy-paste docstring error

Notes

Callers should only set this property if their HLSL does not rely on constructs that require SPIRV normalization, such as Structured Buffers. Incorrect use may produce invalid or unexpected output.

References

#202
#203

[lammmab]

Bump for visibility–
Once this is merged, we can drop our compile times in half :).

[Pucas01]

I would love for this to get merged

[thatcosmonaut]

Looks good, could we add a note that this shouldn't be used with Stuctured Buffers in the prop comment?

Also requesting comment from @madebr

[madebr]

My only comment would've been about API design and long-term stability, but a property is very non-intrusive.

[lammmab]

Thanks guys! I'll add the note and we can get this merged.

[thatcosmonaut]

Merged, thanks!