[llvm] [llvm-mca][Darwin] Fix crash on .subsections_via_symbols in asm input (PR #182694)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 commented:

This needs a test. The PR description also looks LLM generated. This is strongly discourage according to https://llvm.org/docs/AIToolPolicy.html and a more concise version would be helpful.

https://github.com/llvm/llvm-project/pull/182694