Make it compile for WP7 again

TypeForwardedTo is not availible on WP7

Rx/NET/Source/Common.targets

@@ -155,6 +155,8 @@
       Profile88  = .NET for Windows Store apps, .NET Framework 4, Silverlight 4, Windows Phone 7.5
       Profile96  = .NET for Windows Store apps, .NET Framework 4.0.3, Silverlight 4, Windows Phone 7.5
       Profile014 = .NET for Windows Store apps, .NET Framework 4.5, Silverlight 4, Windows Phone 7.5	  
+      TODO: CHANGE TO Profile136 and test when running VS 2012
+      Profile136 = .NET for Windows Store apps, .NET Framework 4, Silverlight 5, Windows Phone 8 
       -->
     <TargetFrameworkProfile>Profile37</TargetFrameworkProfile>
     <NoStdLib>true</NoStdLib>

Rx/NET/Source/System.Reactive.Interfaces/IObservable.cs

@@ -18,7 +18,7 @@ namespace System
         IDisposable Subscribe(IObserver<T> observer);
     }
 }
-#else
+#elif !WINDOWSPHONE7 // TypeForwardedTo is not presen on windows phone 7 so we can't really target
 [assembly: System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.IObservable<>))]
 #endif
 

Rx/NET/Source/System.Reactive.Interfaces/IObserver.cs

@@ -30,6 +30,6 @@ namespace System
         void OnCompleted();
     }
 }
-#else
+#elif !WINDOWSPHONE7 // TypeForwardedTo is not presen on windows phone 7 so we can't really target
 [assembly: System.Runtime.CompilerServices.TypeForwardedTo(typeof(System.IObserver<>))]
 #endif