[llvm] [BOLT][DWARF][NFC] Fix DebugStrOffsetsWriter (PR #100672)

[Alexander Yermolovich via llvm-commits]

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@@ -906,6 +906,8 @@ void DebugStrOffsetsWriter::finalizeSection(DWARFUnit &Unit,
   }
 
   StrOffsetSectionWasModified = false;
+  assert(DebugStrOffsetFinalized.insert(Unit.getOffset()).second == true &&
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ayermolo wrote:

I think you can just do:
DebugStrOffsetFinalized.insert(Unit.getOffset()).second
maybe add "for a CU" to error message.
Also add assert in updateAddressMap to check we don't call it on already finalized CU. 

https://github.com/llvm/llvm-project/pull/100672