[clang] [clang][PowerPC] Do not extend _BitInt arguments and returns on PPC64 (PR #231734)

[Manjunath S Matti. via cfe-commits]

mmatti-sw wrote:

Understood, thanks. I’ll keep this PR as a draft until the ABI supplement settles the _BitInt question. Is there a place where that discussion happens that I can follow or contribute to?

https://github.com/llvm/llvm-project/pull/231734