[clang] [Driver] Hook up Haiku PowerPC support (PR #69134)

[Qiu Chaofan via cfe-commits]

ecnelises wrote:

Ah, I meant potential changes to `llvm/lib/Target` and `llvm/lib/MC`. But I did search in backend using FreeBSD as keyword for example, few places need to support it explicitly. If Haiku uses similar ABI and binary format to Linux or FreeBSD, that makes sense.

https://github.com/llvm/llvm-project/pull/69134