[compiler-rt] [libcxx] CompilerRT: Normalize COMPILER_RT_DEFAULT_TARGET_TRIPLE (PR #89234)

[David Spickett via llvm-commits]

DavidSpickett wrote:

To be clear, the libcxx is "make it work" not "is correct". I agree with Peter that the normalisation does not look correct.

https://github.com/llvm/llvm-project/pull/89234