[dev.regabi] cmd/compile: intercept the making of OADDR nodes

[dev.regabi] cmd/compile: intercept the making of OADDR nodes

This is a mechanical change to intercept the construction of
all OADDR nodes. We will use the new nodAddr and nodAddrAt
functions to compute the Addrtaken bit.

Change-Id: I90ee3acb8e32540a198a9999284573418729f422
Reviewed-on: https://go-review.googlesource.com/c/go/+/275694
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>
Reviewed-by: Dan Scales <danscales@google.com>