[clang] [HLSL][Driver][SPIRV] Add -fspv-use-legacy-buffer-matrix-order flag (PR #214575)

[Helena Kotas via cfe-commits]

hekota wrote:

> > Hmm maybe, let me prototype something... but this is still adding a new builtin is that ok?

I don't think the problem are the new builtins, but that they are duplicating what an existing builtin already handles.


https://github.com/llvm/llvm-project/pull/214575