Merge pull request #298 from ktopley-apple/dispatch-time-resync

Synchronize the Linux and Darwin overlay versions of Time.swift
diff --git a/src/swift/Time.swift b/src/swift/Time.swift
index d7d49c9..5522758 100644
--- a/src/swift/Time.swift
+++ b/src/swift/Time.swift
@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See http://swift.org/LICENSE.txt for license information
@@ -78,13 +78,14 @@
 	}
 }
 
-public func <(a: DispatchTime, b: DispatchTime) -> Bool {
-	if a.rawValue == ~0 || b.rawValue == ~0 { return false }
-	return a.rawValue < b.rawValue
-}
+extension DispatchTime {
+	public static func < (a: DispatchTime, b: DispatchTime) -> Bool {
+		return a.rawValue < b.rawValue
+	}
 
-public func ==(a: DispatchTime, b: DispatchTime) -> Bool {
-	return a.rawValue == b.rawValue
+	public static func ==(a: DispatchTime, b: DispatchTime) -> Bool {
+		return a.rawValue == b.rawValue
+	}
 }
 
 public struct DispatchWallTime : Comparable {
@@ -106,17 +107,20 @@
 	}
 }
 
-public func <(a: DispatchWallTime, b: DispatchWallTime) -> Bool {
-	if b.rawValue == ~0 {
-		return a.rawValue != ~0
-	} else if a.rawValue == ~0 {
-		return false
+extension DispatchWallTime {
+	public static func <(a: DispatchWallTime, b: DispatchWallTime) -> Bool {
+		let negativeOne: dispatch_time_t = ~0
+		if b.rawValue == negativeOne {
+			return a.rawValue != negativeOne
+		} else if a.rawValue == negativeOne {
+			return false
+		}
+		return -Int64(bitPattern: a.rawValue) < -Int64(bitPattern: b.rawValue)
 	}
-	return -Int64(bitPattern: a.rawValue) < -Int64(bitPattern: b.rawValue)
-}
 
-public func ==(a: DispatchWallTime, b: DispatchWallTime) -> Bool {
-	return a.rawValue == b.rawValue
+	public static func ==(a: DispatchWallTime, b: DispatchWallTime) -> Bool {
+		return a.rawValue == b.rawValue
+	}
 }
 
 public enum DispatchTimeInterval {