[llvm] [LLVM] Adjust argument passing for `APInt`. NFC. (PR #81814)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon commented:

No objections, but splitting this into separate focused patches might be cleaner:

- [ ] simplifyDemandedVectorEltsIntrinsic refactor
- [ ] PatternMatch change
- [ ] remaining const APInt& arguments
- [ ] use of std::move in constructors

https://github.com/llvm/llvm-project/pull/81814