[clang] [llvm] [BOLT] Add --ba flag to deprecate --nl (PR #164257)

[Amir Ayupov via cfe-commits]

https://github.com/aaupov commented:

Please check the handling for deprecated options (e.g. `DeprecatedICFNumericOptionParser` or `DeprecatedSplitFunctionOptionParser`) to warn the user about the old flag.

https://github.com/llvm/llvm-project/pull/164257