[llvm] [NFC] Add DIExpression::extractLeadingOffset (PR #97719)

[Stephen Tozer via llvm-commits]

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@@ -2982,6 +2982,16 @@ class DIExpression : public MDNode {
   /// return true with an offset of zero.
   bool extractIfOffset(int64_t &Offset) const;
 
+  /// Assuming that the expression operates on an address, extract a constant
+  /// offset and the succsessive ops. Return false if the expression contains
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SLTozer wrote:

```suggestion
  /// offset and the successive ops. Return false if the expression contains
```

https://github.com/llvm/llvm-project/pull/97719