[compiler-rt] CompilerRT: Normalize COMPILER_RT_DEFAULT_TARGET_TRIPLE (PR #88835)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

Thanks @DavidSpickett! It's good to see that this issue isn't specific for the windows target - I guess it goes for any `armv*` target arch, where the target is implicitly thumb only.

https://github.com/llvm/llvm-project/pull/88835