[llvm] [ObjectYAML][ELF] Report incorrect offset to generate notes (PR #118741)

[Igor Kudrin via llvm-commits]

igorkudrin wrote:

> I'm not sure I understand what the benefit is of adding this error to yaml2obj?

This helps to prevent the accidental generation of invalid note entries. If the current offset in `CBA` is not aligned as expected, the `namesz`, `descsz`, `type`, and `name` fields of the first entry would be aligned differently than its descriptor and all other note entries in the section, making the first entry malformed.

> With the error added, how would somebody generate a note section that wasn't correctly aligned?

At least, they can still use `Content:` instead of `Notes:`, or an empty array for `Notes:`.

https://github.com/llvm/llvm-project/pull/118741