[clang] [DebugInfo] Correct the line attribution for IF branches (PR #108300)

[Nikita Popov via cfe-commits]

nikic wrote:

Nice artifact size improvements: https://llvm-compile-time-tracker.com/compare.php?from=be0b1142df7733633354ef1f73d0379bcd2ccb54&to=53abbced3032b555d43f5b91fafa741c8a11a050&stat=size-file

https://github.com/llvm/llvm-project/pull/108300