[Toybox] [PATCH] Improve file(1)'s ELF support.

[Ed Maste]

> Exactly my problem: I dunno what success looks like here.
>
> (What does NT GNU mean anyway? GNU/Windows NT?)

NT is just a prefix (Note Type, I guess). NT_GNU_ because it's a note
type defined originally by the GNU toolchain (now also implemented in
LLVM's lld).

Probably the most useful documentation on the Build ID is this design
doc from Fedora:
https://fedoraproject.org/wiki/Releases/FeatureBuildId

The short version is that the build ID is just a unique identifier for
the binary. The most common case is that is either a md5 or sha1 hash
of some portion of the binary's content, but a randomly generated
Build ID is also valid. So reporting an inferred and possibly
incorrect type provides little value, other than output compatibility
with the Zoulas file.