Calendar: remove unnecessary return assignments (#1511)
Calendar: remove unnecessary return assignments (#1511)

Cherry-pick of
https://github.com/apple/swift/commit/68e76535bc1dc1b126dd7d81dfe8b1de68924e21
parkera/swift-corelibs-foundation,e78l/swift-corelibs-foundation,e78l/swift-corelibs-foundation,JGiola/swift-corelibs-foundation,JGiola/swift-corelibs-foundation,JGiola/swift-corelibs-foundation,alblue/swift-corelibs-foundation,parkera/swift-corelibs-foundation,apple/swift-corelibs-foundation,e78l/swift-corelibs-foundation,JGiola/swift-corelibs-foundation,parkera/swift-corelibs-foundation,e78l/swift-corelibs-foundation,apple/swift-corelibs-foundation,alblue/swift-corelibs-foundation,apple/swift-corelibs-foundation,alblue/swift-corelibs-foundation,parkera/swift-corelibs-foundation,alblue/swift-corelibs-foundation,apple/swift-corelibs-foundation,alblue/swift-corelibs-foundation,parkera/swift-corelibs-foundation,JGiola/swift-corelibs-foundation,apple/swift-corelibs-foundation,e78l/swift-corelibs-foundation