[llvm] [IR] Add nowrap flags for trunc instruction (PR #85592)

[Yingwei Zheng via llvm-commits]

================
@@ -386,11 +394,17 @@ void Instruction::setNonNeg(bool b) {
 }
 
 bool Instruction::hasNoUnsignedWrap() const {
-  return cast<OverflowingBinaryOperator>(this)->hasNoUnsignedWrap();
+  if (auto Inst = cast<OverflowingBinaryOperator>(this))
----------------
dtcxzyw wrote:

```suggestion
  if (auto *Inst = dyn_cast<OverflowingBinaryOperator>(this))
```

https://github.com/llvm/llvm-project/pull/85592