find_linkage_metas is unused

[jdm]

From attr.rs in libsyntax, find_linkage_metas does not appear to have any callers in rustc. Seems like a good candidate for removal.

[kaseyc]

Should this be removed? Or it is still under discussion?

[nathantypanski]

AFAICT this code is dead. Sending a PR, maybe someone will tell me why it needs to stay.

[nathantypanski]

Blergh. Sorry for dirtying this bug report. It took me a while to go through the grep output, and after a couple of tries I just gave up.