[llvm] [ThinLTO]Sort imported GUIDs before cache key update (PR #92622)

[Fangrui Song via llvm-commits]

https://github.com/MaskRay approved this pull request.

Thanks! https://abseil.io/docs/cpp/guides/container#iteration-order-instability and DenseMap/StringMap "randomize" the iteration order to catch mistakes, but libstdc++/libc++ unordered_{set,map} haven't implemented this technique. (Many simple concepts are extremely difficult to implement portably in libc++...)

https://github.com/llvm/llvm-project/pull/92622