[llvm] [MachineVerifier] Report errors from one thread at a time (PR #111605)

[Matt Arsenault via llvm-commits]

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@@ -231,6 +239,39 @@ struct MachineVerifier {
   LiveStacks *LiveStks = nullptr;
   SlotIndexes *Indexes = nullptr;
 
+  class ReportedErrors {
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arsenm wrote:

Document 

https://github.com/llvm/llvm-project/pull/111605