[llvm] Reduce llvm-gsymutil memory usage (PR #139907)

[David Blaikie via llvm-commits]

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@@ -257,6 +259,8 @@ class DWARFUnit {
 
   std::shared_ptr<DWARFUnit> DWO;
 
+  mutable std::recursive_mutex FreeDIEsMutex;
+
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dwblaikie wrote:

Previously we tried pretty hard to keep the multithreading support isolated in the ThreadSafeDWARFContext or something like that - could you try to do the same now? (move the locking to the ThreadSafeDWARFContext, probably)

(& yeah, please undo the unrelated formatting changes in this file - it's hard to review with them in)

https://github.com/llvm/llvm-project/pull/139907