[llvm] [ADT] Update hash function of uint64_t for DenseMap (PR #95734)

[Aaron Ballman via llvm-commits]

AaronBallman wrote:

>It would be nice to get someone expert in state-of-the-art hash functions and hash tables to review this.

@chandlerc -- any chance you could weigh in here?

https://github.com/llvm/llvm-project/pull/95734