Update vpc-sc.tf - manage empty perimeters. (#530)
Update vpc-sc.tf - manage empty perimeters. (#530)

* Update vpc-sc.tf - manage empty perimeters.

Co-authored-by: Ludovico Magnocavallo <806dfc92dde3cfd3ba4356fe553701104dfcb202@google.com>
GoogleCloudPlatform/cloud-foundation-fabric,GoogleCloudPlatform/cloud-foundation-fabric,GoogleCloudPlatform/cloud-foundation-fabric,GoogleCloudPlatform/cloud-foundation-fabric