[llvm] [llvm-readobj][NFC] Don't use startLine in a middle of a line in ObjDumper. (PR #102071)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

Behaviour like whitespace/indentation should have testing with `--strict-whitespace` and `--match-full-lines` enabled, so that we don't regress the formatting in the future. Does that currently exist for the options impacted here? If not, I think it would be worthwhile adding it.

https://github.com/llvm/llvm-project/pull/102071