[clang] [Clang][Driver][AArch64] Add support for aarch64-amazon-linux triple (PR #109263)

[Fangrui Song via cfe-commits]

MaskRay wrote:

I don't think we've reached consensus. The comment there serves a purpose and specifically discourages people from doing this mismatching triple things.

If the GCC installation on Amazon Linux uses `aarch64-amazon-linux`, and the default target triple of the Clang is `aarch64-unknown-linux-gnu`, it's by design that the GCC installation doesn't got picked.
(The code here is more loose in that `--target=aarch64-unknown-linux-musl` would pick up `aarch64-amazon-linux`.)

If for some reason you have a Clang with the default target triple `aarch64-unknown-linux-gnu`,
you could change `clang` to a wrapper that does `real/clang --target=aarch64-amazon-linux`.

While I appreciate @stewartsmith 's long context, I don't think it provides real justification.


https://github.com/llvm/llvm-project/pull/109263