[llvm] [ExceptionDemo] Correct and update example ExceptionDemo (PR #69485)

[via llvm-commits]

epitavy wrote:

It works as expected for me, except that some values are wrong.
```
Gen: About to throw exception type <2> in throwFunct.
Gen: Exception type <96> received (stack unwound)  in innerCatchFunct.
                    ^^^^
```
96 should be 2, but the bug was already here, and I don't know how to fix that

https://github.com/llvm/llvm-project/pull/69485