This fixes more minor issue when constructing the descriptor in that
delimited encoded message fields are not considered properly as groups.
Change-Id: I714a227a0f8d256fa7430c526844e8e94acdda33
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/564816
Reviewed-by: Michael Stapelberg <stapelberg@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Lasse Folger <lassefolger@google.com>
