cmd/link, cmd/internal/goobj: update constants, regenerate testdata

cmd/link, cmd/internal/goobj: update constants, regenerate testdata

The constants in cmd/internal/goobj had gone stale (we had three copies of
these constants, working on reducing that was what got me to noticing this).

Some of the changes to link.hello.darwin.amd64 are the change from absolute
to %rip-relative addressing, a change which happened quite a while ago...

Depends on http://golang.org/cl/9113.

Fixes #10501.

Change-Id: Iaa1511f458a32228c2df2ccd0076bb9ae212a035
Reviewed-on: https://go-review.googlesource.com/9105
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>