[llvm] [llvm-nm] Introduce synthetic flag (PR #138232)

[Vladislav Khmelevsky via llvm-commits]

yota9 wrote:

@jh7370 Hello! Sure, would add couple of lines to documentation. The build failures seems to be unrelated, all tests are passed, I would check out more precise a bit later. Thank you, waiting for your review!

https://github.com/llvm/llvm-project/pull/138232