[dev.link] cmd/link: accept more types in Xcoffadddynrel

[dev.link] cmd/link: accept more types in Xcoffadddynrel

In dodata we overwrite symbol types to SDATA. Now we'll stop
doing that, so accept more symbol types here. This is basically
a list of all writeable types handled in dodata that could appear
in XCOFF.

Change-Id: Iee35369162f5acd59806a3f0e6c8d3682620067e
Reviewed-on: https://go-review.googlesource.com/c/go/+/230310
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>