[llvm] [LLVM][TableGen] Fix Windows failure in DecoderEmitter (PR #136310)

[Rahul Joshi via llvm-commits]

jurahul wrote:

FYI, it hits this check in VC++ vector implementation:

```
        _STL_VERIFY(
            _Mycont->_Myfirst <= _Ptr && _Ptr < _Mycont->_Mylast, "can't dereference out of range vector iterator");
```

https://github.com/llvm/llvm-project/pull/136310