[llvm] [llvm-jitlink] Add optional index argument in jitlink-check stub_addr() expressions (PR #78369)

[Stefan Gränitz via llvm-commits]

weliveindetail wrote:

I made a dedicated review for the first commit in https://github.com/llvm/llvm-project/pull/78365. Once it's through I will rebase this one and the NFC commit will vanish.

https://github.com/llvm/llvm-project/pull/78369