cmd/go: skip over all workspace modules in go mod verify

This was a remaining place where we made the assumption that there is
only one workspace module. So we'd only skip the first workspace
module when running go mod verify. Instead skip over the first
MainModules.Len() modules of the buildlist, which are all the main
modules.

Fixes #54372

Change-Id: Ife687c907ae4326759c43cc35f78d429d5113b19
Reviewed-on: https://go-review.googlesource.com/c/go/+/485475
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>

0 files changed, 0 insertions, 0 deletions