[test] Adjusting stdlib ocurrences where class syntax is used for protocol inheritance

Author: LucianoPAlmeida

stdlib/public/Darwin/CoreFoundation/CoreFoundation.swift

@@ -12,7 +12,7 @@
 
 @_exported import CoreFoundation
 
-public protocol _CFObject: class, Hashable {}
+public protocol _CFObject: AnyObject, Hashable {}
 extension _CFObject {
   public var hashValue: Int {
     return Int(bitPattern: CFHash(self))

stdlib/public/core/BridgeObjectiveC.swift

@@ -681,7 +681,7 @@ public func _conditionallyBridgeFromObjectiveC_bridgeable<T:_ObjectiveCBridgeabl
 }
 
 public // SPI(Foundation)
-protocol _NSSwiftValue: class {
+protocol _NSSwiftValue: AnyObject {
   init(_ value: Any)
   var value: Any { get }
   static var null: AnyObject { get }

stdlib/public/core/ExistentialCollection.swift

@@ -1641,7 +1641,7 @@ extension AnyRandomAccessCollection {
 //===----------------------------------------------------------------------===//
 
 @usableFromInline
-internal protocol _AnyIndexBox: class {
+internal protocol _AnyIndexBox: AnyObject {
   var _typeID: ObjectIdentifier { get }
 
   func _unbox<T: Comparable>() -> T?