Other binary formats to follow.

Using our own note instead of the GNU build ID note because
we are not the GNU project, and I can't guarantee that the semantics
of our note and the semantics of the GNU note will match forever.
(Also they don't match today.)

For #11048.

Change-Id: Iec7e5a2e49d52b6d3a51b0aface2de7c77a45491
Reviewed-on: https://go-review.googlesource.com/10706Reviewed-by: Ian Lance Taylor <iant@golang.org>