cmd/go/internal/modload: replace references to modfetch.Fetcher_
This commit replaces references of modfetch.Fetcher_ with
modload.State.Fetcher() in the modload package. Note that the
constructor `NewState` still intentionally references the global
variable. This will be refactored in a later commit.
Change-Id: Ia8cfb41a81b0e29043694bc0f0f33f5a2f4920c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/724243 Reviewed-by: Michael Matloob <matloob@golang.org> Reviewed-by: Michael Matloob <matloob@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>