cmd/go: fix not print GCCGO when it's not the default
Fixes #69994
Change-Id: I2a23e5998b7421fd5ae0fdb68303d3244361b341
Reviewed-on: https://go-review.googlesource.com/c/go/+/671635 Reviewed-by: Michael Matloob <matloob@golang.org> Reviewed-by: Michael Matloob <matloob@google.com> Reviewed-by: Sean Liao <sean@liao.dev>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Knyszek <mknyszek@google.com>