[clang] [PowerPC] Support -mno-red-zone option (PR #94581)

[Chen Zheng via cfe-commits]

chenzheng1030 wrote:

> No. `-disable-red-zone` does nothing but add `noredzone` IR attribute to functions. We need to add cases to test for `noredzone` behavior on PPC (arm and x86 have).

Yeah, go ahead to add some backend tests first to make sure we have good functionality for `noredzone` attribute. Thanks.

https://github.com/llvm/llvm-project/pull/94581