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

[Peter Waller via cfe-commits]

peterwaller-arm wrote:

> The CMake build system could be adjusted to make -DLLVM_DEFAULT_TARGET_TRIPLE=aarch64-amazon-linux implied on Amazon Linux, though.

Thanks - Is there precedence for this? Do you have any ideas about how to detect the correct default triple?

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