[llvm] [dsymutil] Remove paper trail warnings (PR #67041)

[via llvm-commits]

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avl-llvm wrote:

I do not see how to comment exact line if it is not part of already changed lines... So I put comment in start of the file. The DWARFFile::Warnings can also be removed. And the same for the DWARFLinkerParallel\DWARFFile.h.

https://github.com/llvm/llvm-project/pull/67041