[dev.link] cmd/link: add hooks for sorting loader.Reloc by offset
[dev.link] cmd/link: add hooks for sorting loader.Reloc by offset

Add support for supporting loader.Reloc by offset, needed by host
object loaders.

Change-Id: I5ac0702ee74ad71531f443e6215558d8151e3a4c
Reviewed-on: https://go-review.googlesource.com/c/go/+/211306
Run-TryBot: Than McIntosh <4b2922593166fc595a9b1a408f34f5d3817fe9d2@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Cherry Zhang <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>
Reviewed-by: Jeremy Faller <b3f594e10a9edcf5413cf1190121d45078c62290@golang.org>

akutz/go,cloudflare/go,akutz/go,cloudflare/go,nawawi/go,CAFxX/go,cloudflare/go,nawawi/go,nawawi/go,CAFxX/go,golang/go,cloudflare/go,CAFxX/go,golang/go,CAFxX/go,akutz/go,nawawi/go,golang/go,CAFxX/go,golang/go,akutz/go,golang/go,akutz/go,golang/go,golang/go,CAFxX/go,nawawi/go,cloudflare/go,akutz/go,akutz/go,golang/go,nawawi/go,CAFxX/go,cloudflare/go,cloudflare/go,CAFxX/go,nawawi/go,cloudflare/go,nawawi/go,akutz/go