cmd/internal/obj,cmd/link: access global data via GOT in -dynlink mode on loong64

Updates #58784

Change-Id: Ic98d10a512fea0c3ca321ab52693d9f6775126a6
Reviewed-on: https://go-review.googlesource.com/c/go/+/480875


Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Meidan Li <limeidan@loongson.cn>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: WANG Xuerui <git@xen0n.name>
Reviewed-by: WANG Xuerui <git@xen0n.name>