[llvm] [llvm][lli] fix lli crash when run variable arguments function as a interpret (PR #173719)

[via llvm-commits]

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@@ -1082,7 +1082,7 @@ void Interpreter::visitVAStartInst(VAStartInst &I) {
   GenericValue ArgIndex;
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Fushj89 wrote:

The `VAList ` var  in `visitVAArgInst` function  hava a little confused for me. I think the result of `VAStartInst.getOperand(0)` should be named `VAList `,  for example, the var `%2` in ir  should represent the `VAList`. 
```
define i32 @sum(i32 %0, ...)  {
  %2 = alloca ptr, align 8
  call void @llvm.va_start.p0(ptr nonnull %2)
.....
```

It may be more appropriate to rename the variable 'VAList' in`visitVAArgInst`  to 'ArgIndex' or   'VAListArgIndex' .
I am beginner and clear changes for review, so didn't change the name. 



https://github.com/llvm/llvm-project/pull/173719