Local Build ID Directory Lookup (DEBUGINFOD_LOCAL_PATH)

[Frank Ch. Eigler]

Hi -

> Hmm, how would the effective behavior of this differ from directly
> returning the path? The symlink could become invalid at any time [...]

Effective behaviour is about the same, but code logic and explanation
is simpler.

> It would make sense if the cache were made to contain a hard link to the
> file if it were on the same filesystem as the cache [...]

And this could be a QoI implementation detail: prefer hardlink, fall
back to symlink.

- FChE