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

[Chuanqi Xu via llvm-commits]

ChuanqiXu9 wrote:

What's updated:
- Adopt @nikic 's opinion to not use interfaces from `ADT/Hashing.h`.
- Adopt @nikic 's opinion to add the overload for `unsigned long`.
- Adopt @MaskRay 's opinion to use `detail::combineHashValue`

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