[llvm] [ADT] Use CMake to detect host endianness (NFC) (PR #164054)

[Jakub Kuderski via llvm-commits]

https://github.com/kuhar commented:

Is this compatible with bazel? I know the support level is much lower than cmake, but maybe worth checking that they can do something sensible here.

https://github.com/llvm/llvm-project/pull/164054