[release-branch.go1.21] cmd/go/internal/modcmd: correctly filter out main modules in verify
This change fixes a bug where we incorrectly filtered out the main
modules from the beginning of the build list before verifying them. We
made the assumption that the first MainModules.Len() entries of the
build list were the main modules, but now it can contain the go and
toolchain version entries, so removing the first MainModules.Len()
entries could leave main module names in the build list if any of
their names sorted after the string 'go'.
For #62663
Fixes #65851
Change-Id: I35ab6857a556f58d306303322afe24c48fc8b38f
Reviewed-on: https://go-review.googlesource.com/c/go/+/565378
Reviewed-by: Bryan Mills <bcmills@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
(cherry picked from commit
3f60da7944352d7f2d4a04830c0612457643016c)
Reviewed-on: https://go-review.googlesource.com/c/go/+/565755
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>