Adding the default label/mapping is important because:
1. Lookups of services without an selinux label should generate
a denial.
2. In permissive mode, lookups of a service without a label should be
be allowed, without the default label service manager disallows
access.
3. We can neverallow use of the default label.
Bug: 37762790
Test: Build and flash policy onto Marlin with unlabeled vendor services.
Add/find of unlabeled vendor services generate a denial.
Change-Id: I66531deedc3f9b79616f5d0681c87ed66aca5b80
