[llvm] [RemoveDIs] Add additional debug-mode verifier checks (PR #84308)

[Stephen Tozer via llvm-commits]

https://github.com/SLTozer commented:

Should this be Check, or CheckDI? On the one hand this is check that shouldn't fail due to a bad input, but only due to an error in LLVM itself; on the other hand, if it could be resolved by stripping debug info then it might be better to allow that in case someone encounters this in the wild? I'm not strongly opinionated either way, since there's precedent for internal debug info errors being a verifier failure.

https://github.com/llvm/llvm-project/pull/84308