[llvm] Reduce llvm-gsymutil memory usage (lambda-free, and less locking) (PR #97640)

[David Blaikie via llvm-commits]

https://github.com/dwblaikie commented:

Hmm, now this is a bit simpler - how bad would it be if it indirected through the DWARFContext & used the existing context-level locking? (perhaps it's a losing battle to try to avoid the threading complexity leaking out of the ThreadSafeDWARFContext, but I'll at least ask)

Like if DWARFContext had a somewhat awkward "doThisThingThreadSafely(function_ref<void()>)" and these APIs called that, which held the lock and did the work (or with the non-thread-safe DWARFContext, just called back immediately)

https://github.com/llvm/llvm-project/pull/97640