build-ids, .debug_sup and other IDs

[Frank Ch. Eigler]

Hi -

> For dwz --dwarf-5, if it produced a .note.gnu.build-id, it would produce
> the same one, but I thought that if I produced that, then consumers could
> keep using that instead of .debug_sup which is the only thing defined
> in the standard, so in the end dwz --dwarf-5 only produces .debug_sup
> on both the referrers side and on the side of supplemental object file
> as DWARF specifies.

Right, but build-ids are still in normal binaries -- just not the
dwz-commonized files created by "dwz --dwarf-5"?  So our toolchains
still process build-ids routinely for all the other uses.  By omitting
the build-id on the dwz-generated files, we're forcing a flag day on
all our consumer tools.  (Does dwz'd dwarf5 even work on gdb
etc. now?)  ISTM tool backward compatibility is more important, so
I would suggest dwz generate -both- identifiers.

- FChE