Added support for dumping line number information in llvm-objdump.
The llvm-objdump test looks good to me. Instead of # REQUIRES: powerpc-registered-target, you can add a lit.local.cfg with if not 'PowerPC' in config.root.targets:\n config.unsupported = True
For the parts that aren't required and can't be exercised at all, it seems like you should be able to just leave them out? For those parts that are required, you could add gtest unit testing to cover them. See llvm/unittest/Object for some examples.