Fix mistake in tvOS availability

Author: parkera

stdlib/public/SDK/Foundation/Calendar.swift

@@ -426,7 +426,7 @@ public struct Calendar : CustomStringConvertible, CustomDebugStringConvertible,
     /// - parameter component: A calendar component.
     /// - parameter date: The specified date.
     /// - returns: A new `DateInterval` if the starting time and duration of a component could be calculated, otherwise `nil`.
-    @available(OSX 10.12, iOS 10.0, tvOS 12.0, watchOS 3.0, *)
+    @available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)
     public func dateInterval(of component: Component, for date: Date) -> DateInterval? {
         var start : Date = Date(timeIntervalSinceReferenceDate: 0)
         var interval : TimeInterval = 0
@@ -703,7 +703,7 @@ public struct Calendar : CustomStringConvertible, CustomDebugStringConvertible,
     ///
     /// - parameter date: The date contained in the weekend.
     /// - returns: A `DateInterval`, or nil if the date is not in a weekend.
-    @available(OSX 10.12, iOS 10.0, tvOS 12.0, watchOS 3.0, *)
+    @available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)
     public func dateIntervalOfWeekend(containing date: Date) -> DateInterval? {
         var nsDate : NSDate? = nil
         var ti : TimeInterval = 0
@@ -748,7 +748,7 @@ public struct Calendar : CustomStringConvertible, CustomDebugStringConvertible,
     /// - parameter date: The date at which to begin the search.
     /// - parameter direction: Which direction in time to search. The default value is `.forward`.
     /// - returns: A `DateInterval`, or nil if weekends do not exist in the specific calendar or locale.
-    @available(OSX 10.12, iOS 10.0, tvOS 12.0, watchOS 3.0, *)
+    @available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)
     public func nextWeekend(startingAfter date: Date, direction: SearchDirection = .forward) -> DateInterval? {
         // The implementation actually overrides previousKeepSmaller and nextKeepSmaller with matchNext, always - but strict still trumps all.
         var nsDate : NSDate? = nil