cmd/compile: fixing writebarrier.go for -G=3

This is caused by some nodes didn't carry the real line number.
Noder1 wraps these node with ir.ParenExpr. To fix this issue,
wraps this node like what noder1 does.

Change-Id: I212cad09b93b8bf1a7adfad416d229d15711918a
Reviewed-on: https://go-review.googlesource.com/c/go/+/349769


Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Keith Randall <khr@golang.org>