Packages in modules don't have a Target set for them, so the current
logic for determining staleness always reports them as stale. Instead it
should be reporting whether "go install" would do anything, and sholud
be false after a go install. If a package does not have a Target,
instead check to see whether we've cached its build artifact.
Change-Id: Ie7bdb234944353f6c2727bd8bf939cc27ddf3f18
Reviewed-on: https://go-review.googlesource.com/c/go/+/444619
Run-TryBot: Michael Matloob <matloob@golang.org> Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Michael Matloob <matloob@golang.org>