[llvm] r217909 - [llvm-objdump] improve error reporting of bad mach-o ordinals

[Rafael Espíndola]

> I don’t know how to create a test file with bad ordinals in order to create a test case for the error handling changes…

In the past I have just used hexedit to patch in an invalid number in a .o.

Making sure error paths are tested is important to make sure we don't
end up with bogus error handling like the one removed in r219314 and
to make it safe to refactor the error handling in the future.

Cheers,
Rafael