[clang] [llvm] [CodeView] Flatten cmd args in frontend for LF_BUILDINFO (PR #106369)

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nebulark wrote:

I always set Argv0 and Commandline, even if they are just an empty string. Some tools had issues if those were not set.
We already did use the empty string for BuildInfoRecord::TypeServerPDB, so now its also more consistent.

So the offset changed from 0x (null) to the empty string offset for some tests and is the same offset as the 4th entry (BuildInfoRecord::TypeServerPDB) in LF_BUILDINFO




https://github.com/llvm/llvm-project/pull/106369