cmd/compile: fix missing export/import init nodes of builtins that allow multiple...

cmd/compile: fix missing export/import init nodes of builtins that allow multiple arguments

Fixes #52590

Change-Id: Ibd0852ae2a9ad8e4598e93320daff1b3c196929f
Reviewed-on: https://go-review.googlesource.com/c/go/+/402854
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Keith Randall <khr@google.com>