[llvm] To allow truncation for getIntN. (PR #178834)

[Daniel Chen via llvm-commits]

DanielCChen wrote:

> This is incorrect, you need to look at the callers to determine how they need to be changed.

Thanks for the quick review!
Sure. I will check the downstream code and see if we can use an alternative.
If the intention of `getIntN` is to not truncate, should the comment be fixed so it is not misleading?
It currently reads:
```  
/// Get a constant N-bit value, zero extended or truncated from
/// a 64-bit value.
```

https://github.com/llvm/llvm-project/pull/178834