[llvm] [InstCombine][NFC] Use uint64_t for ExtractIdx in vector_extract fold (PR #225156)

[Yingwei Zheng via llvm-commits]

https://github.com/dtcxzyw commented:

Even if the overflow occurs, at worst we just miss out on an optimization that is virtually impossible to encounter.


https://github.com/llvm/llvm-project/pull/225156