cmd/go: localize computation of deps/depserrors in list
Stop depending on DepsErrors to report errors to the user and instead
only use it and compute it in list. Instead, use Incomplete to figure
out when a package or its depencies have an error, and only if they
do, do the work of finding all those errors.
For #59157
Change-Id: Ied927f53e7b1f66fad9248b40dd11ed960b3ef91
Reviewed-on: https://go-review.googlesource.com/c/go/+/483495
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org> Reviewed-by: Bryan Mills <bcmills@google.com> Reviewed-by: Michael Matloob <matloob@golang.org>