[llvm] [ConstraintSystem] Update comments (PR #127351)

[Florian Hahn via llvm-commits]

================
@@ -73,10 +79,13 @@ bool ConstraintSystem::eliminateUsingFM() {
       unsigned IdxLower = 0;
       auto &LowerRow = RemainingRows[LowerR];
       auto &UpperRow = RemainingRows[UpperR];
+      // Update constant and coefficients of both constraints.
+      // Stops until every coefficient is updated or overflow.
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fhahn wrote:

```suggestion
      // Stops until every coefficient is updated or overflows.
```

https://github.com/llvm/llvm-project/pull/127351