Add missing .NET 4.5 APIs

* System.Text.RegularExpressions.Regex.InfiniteMatchTimeout
* System.Net.HttpStatusCode.UpgradeRequired
* Add System.Reflection.TypeAttributes.WindowsRuntime
* System.Runtime.GCLatencyMode.SustainedLowLatency
* System.UriComponents.NormalizedHost
[WCF]: Add stubs for some missing .NET 4.0/4.5 APIs.