[clang] [lld] [llvm] [lld][llvm/mc] Add support for sdata8 for FDE CIE (PR #174508)

[Farid Zakaria via llvm-commits]

fzakaria wrote:

@MaskRay is it better to remove the clang driver for now to make progress.
Internally we can rely on `-Wa` to pass it in the meantime to the assembler.

What should the discussion be about in the ABI group? I can kickstart it but I am not sure the topic.
The format itself supports multiple byte-encodings so it seems like purely a lack of implementation support.
(This is not adding a new byte-encoding type)

Appreciate any guidance on how to make progress here.
I have a few more contributions in this direction (I sent you an email to maskray.me) about it :bow: 

https://github.com/llvm/llvm-project/pull/174508