cmd/compile/internal/types2: enable Alias types for TestStdlib
This is expected to eliminate a potential race condition
which is causing a flaky test.
Fixes #67260.
Change-Id: I3fd76047136e2d4659a1c551491e371b67e8a7ce
Reviewed-on: https://go-review.googlesource.com/c/go/+/589236
Auto-Submit: Robert Griesemer <gri@google.com> Reviewed-by: Robert Findley <rfindley@google.com> Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>