swift

31fa5fc3 - Sema: Replace UnavailabilityDiagnosticInfo with AvailabilityConstraint.

Sema: Replace UnavailabilityDiagnosticInfo with AvailabilityConstraint. AvailabilityConstraint models a superset of UnavailabilityDiagnosticInfo and will become the currency type for unsatisfied availability everywhere. NFC.