[clang] [clang][RISCV] Extend intrinsic size check variable from 16 -> 32 bits. NFC (PR #111481)

[Brandon Wu via cfe-commits]

4vtomat wrote:

> I think we need to change
> 
> ```
> struct RVVOverloadIntrinsicDef {
>   // Indexes of RISCVIntrinsicManagerImpl::IntrinsicList.
>   SmallVector<uint16_t, 8> Indexes;
> };
> ```
> 
> and
> 
> ```
>   // Mapping function name to index of IntrinsicList.
>   StringMap<uint16_t> Intrinsics;
> ```
> 
> Those places were both changed by [e0092ea](https://github.com/llvm/llvm-project/commit/e0092eae431956a2fd17f7ea88e7ba26d5e44f7e) in addition to the place you've currently changed.

Oh, nice catch! I didn't even remember I've changed this before lol~

https://github.com/llvm/llvm-project/pull/111481