Get the value of GOARCH from the config instead.
It should have been set to the same as the one from the environment by
default, but may have been overidden by the caller.
Change-Id: If9a6c0ae998c1c72ad2a68fe83c8bb9f5614a189
Reviewed-on: https://go-review.googlesource.com/c/142361
Run-TryBot: Ian Cottrell <iancottrell@google.com>
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>