[clang] [libcxx] [llvm] Triple::normalize: Use none as OS for XX-none-ABI (PR #89638)

[David Spickett via cfe-commits]

DavidSpickett wrote:

Also this change should be release noted with a tip that build scripts may want to change to asking clang for the triple instead.

https://github.com/llvm/llvm-project/pull/89638