emit annotate attribute strings to final debuginfo in object file

Hi,

This is to seek advice whether and how we could put annotate attribute
strings to final debuginfo in object file. I have implemented a POC
patch to illustrate what we really want. The patch is here
⚙ D103549 [POC] Put annotation strings into debuginfo.. The use case is for vmlinux BTF.
Currently vmlinux BTF is generated by pahole by converting vmlinux
dwarf to BTF. The architecture is x86, x86_64, arm64, ppc, etc.

The following are detailed explanations for use cases, a concrete
source example.
I didn't find an easy way to pass such annotate attribute strings to
dwarf. Maybe I am wrong and happy to hear suggestions. Also I "abused"
annotate attributes here, maybe we could have a different one?

The Use Cases