[clang] [Clang][Xtensa] Add Xtensa target. (PR #118008)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

I don't know that we need reaffirmation; the target is already in the backend, so unless there's a call to remove the target, I think Clang's fine to expose it.

That said, if there are signs that the target is only sporadically maintained, reaffirming that's not the case would be a good thing, so I think Eli's question is still a good one to get an answer for.

https://github.com/llvm/llvm-project/pull/118008