Support printing ELF .relr relocations

[bjorn3]

https://maskray.me/blog/2021-10-31-relative-relocations-and-relr has an explanation of the format.

[m4b]

Neat thanks for posting the link! If someone is interested in printing them, as long as they're in goblin, I suspect it won't be very much work :shrug: probably mostly will be deciding how to render it :)